In molecular biology, a carbohydrate-binding module (CBM) is a

protein domain In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of s ...

found in

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...

-active enzymes (for example

glycoside hydrolases Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cel ...

). The majority of these domains have carbohydrate-binding activity. Some of these domains are found on cellulosomal

scaffoldin Cellulosomes are multi-enzyme extracellular complexes. Cellulosomes are associated with the cell surface and mediate cell attachment to insoluble substrates and degrade them to soluble products which are then absorbed. Cellulosome complexes are in ...

proteins. CBMs were previously known as

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

-binding domains. CBMs are classified into numerous families, based on

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

sequence similarity. There are currently (June 2011) 64 families of CBM in the CAZy database. CBMs of

microbial A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

glycoside hydrolase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cel ...

s play a central role in the recycling of photosynthetically fixed

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

through their binding to specific

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

structural

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

s. CBMs can recognise both crystalline and amorphous cellulose forms. CBMs are the most common non-catalytic modules associated with

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

s active in plant cell-wall

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

. Many putative CBMs have been identified by

amino acid sequence Protein primary structure is the linear sequence of amino acids in a peptide or protein. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end. Protein biosynthes ...

alignment Alignment may refer to: Archaeology * Alignment (archaeology), a co-linear arrangement of features or structures with external landmarks * Stone alignment, a linear arrangement of upright, parallel megalithic standing stones Biology * Structu ...

s but only a few representatives have been shown experimentally to have a carbohydrate-binding function.

CBM1

Carbohydrate-binding module family 1 (CBM1) consists of 36 amino acids. This domain contains 4 conserved

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometime ...

residues which are involved in the formation of two

disulfide bonds In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

CBM2

Carbohydrate-binding module family 2 (CBM2) contains two conserved

s - one at each extremity of the domain - which have been shown to be involved in a

disulfide bond In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

. There are also four conserved

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...

s, two of which are involved in cellulose binding.

CBM3

Carbohydrate-binding module family 3 (CBM3) is involved in

binding and is found associated with a wide range of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

l glycosyl hydrolases. The

structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

of this domain is known; it forms a

beta sandwich Beta-sandwich, β-sandwich domains consisting of 80 to 350 amino acids occur commonly in proteins. They are characterized by two opposing antiparallel beta sheets (β-sheets). The number of strands found in such domains may differ from one protei ...

CBM4

Carbohydrate-binding module family 4 (CBM4) includes the two cellulose-binding domains, CBD(N1) and CBD(N2), arranged in tandem at the N terminus of the 1,4-beta-glucanase, CenC, from ''Cellulomonas fimi''. These homologous CBMs are distinct in their selectivity for binding amorphous and not crystalline cellulose. Multidimensional heteronuclear

nuclear magnetic resonance Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...

(NMR) spectroscopy was used to determine the

tertiary structure Protein tertiary structure is the three dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains. Amino acid side chains may int ...

of the 152

N-terminal cellulose-binding

domain Domain may refer to: Mathematics *Domain of a function, the set of input values for which the (total) function is defined **Domain of definition of a partial function **Natural domain of a partial function **Domain of holomorphy of a function * Do ...

from ''C. fimi'' 1,4-beta-glucanase CenC (CBDN1). The tertiary

of CBDN1 is strikingly similar to that of the bacterial 1,3-1,4-beta-glucanases, as well as other sugar-binding

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s with

jelly-roll fold The jelly roll or Swiss roll fold is a protein fold or supersecondary structure composed of eight beta strands arranged in two four-stranded sheets. The name of the structure was introduced by Jane S. Richardson in 1981, reflecting its resemblanc ...

s. CBM4 and CBM9 are closely related.

CBM5

Carbohydrate-binding module family 5 (CBM5) binds chitin. CBM5 and CBM12 are distantly related.

CBM6

Carbohydrate-binding module family 6 (CBM6) is unusual in that it contains two substrate-binding sites, cleft A and cleft B. ''Cellvibrio mixtus'' endoglucanase 5A contains two CBM6 domains, the CBM6 domain at the C-terminus displays distinct ligand binding specificities in each of the substrate-binding clefts. Both cleft A and cleft B can bind cello-

oligosaccharides An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sugar ...

laminarin The molecule laminarin (also known as laminaran) is a storage glucan (a polysaccharide of glucose) found in brown algae. It is used as a carbohydrate food reserve in the same way that chrysolaminarin is used by phytoplankton, especially in diatom ...

preferentially binds in cleft A, xylooligosaccharides only bind in cleft A and beta1,4,-beta1,3-mixed linked

glucans A glucan is a polysaccharide derived from D-glucose, linked by glycosidic bonds. Glucans are noted in two forms: alpha glucans and beta glucans. Many beta-glucans are medically important. They represent a drug target for antifungal medications of ...

only bind in cleft B.

CBM9

Carbohydrate-binding module family 9 (CBM9) binds to crystalline cellulose. CBM4 and CBM9 are closely related.

CBM10

Carbohydrate-binding module family 10 (CBM10) is found in two distinct sets of

s with different functions. Those found in

aerobic bacteria Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cell ...

bind cellulose (or other carbohydrates); but in

anaerobic fungi Neocallimastigomycota is a phylum containing anaerobic fungi, which are symbionts found in the digestive tracts of larger herbivores. Anaerobic fungi were originally placed within phylum Chytridiomycota, within Order Neocallimastigales but later ...

they are protein binding domains, referred to as dockerin domains. The dockerin domains are believed to be responsible for the assembly of a multiprotein cellulase/hemicellulase complex, similar to the

cellulosome Cellulosomes are multi-enzyme extracellular complexes. Cellulosomes are associated with the cell surface and mediate cell attachment to insoluble substrates and degrade them to soluble products which are then absorbed. Cellulosome complexes are in ...

found in certain anaerobic

. In anaerobic

that degrade plant cell walls, exemplified by ''

Clostridium thermocellum ''Acetivibrio thermocellus'' is an anaerobic, thermophilic bacterium. ''A. thermocellusm'' has garnered research interest due to its cellulolytic and ethanologenic abilities, being capable of directly converting a cellulosic substrate into etha ...

'', the dockerin domains of the

catalytic Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

polypeptides Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A p ...

can bind equally well to any

cohesin Cohesin is a protein complex that mediates sister chromatid cohesion, homologous recombination, and DNA looping. Cohesin is formed of SMC3, SMC1, SCC1 and SCC3 ( SA1 or SA2 in humans). Cohesin holds sister chromatids together after DNA rep ...

from the same

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

. More recently, anaerobic fungi, typified by ''Piromyces equi'', have been suggested to also synthesise a cellulosome complex, although the dockerin sequences of the

l and

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

are completely different. For example, the fungal enzymes contain one, two or three copies of the dockerin

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...

in tandem within the catalytic polypeptide. In contrast, all the ''C. thermocellum'' cellulosome catalytic components contain a single dockerin domain. The anaerobic bacterial dockerins are homologous to

EF hand The EF hand is a helix–loop–helix structural domain or ''motif'' found in a large family of calcium-binding proteins. The EF-hand motif contains a helix–loop–helix topology, much like the spread thumb and forefinger of the human hand, in ...

s (calcium-binding motifs) and require calcium for activity whereas the fungal dockerin does not require calcium. Finally, the interaction between cohesin and dockerin appears to be

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

specific in bacteria, there is almost no species specificity of binding within fungal species and no identified sites that distinguish different species. The of dockerin from ''P. equi'' contains two

helical Helical may refer to: * Helix, the mathematical concept for the shape * Helical engine, a proposed spacecraft propulsion drive * Helical spring, a coilspring * Helical plc, a British property company, once a maker of steel bar stock * Helicoil A t ...

stretches and four short beta-strands which form an antiparallel sheet structure adjacent to an additional short twisted parallel strand. The N- and C-termini are adjacent to each other.

CBM11

Carbohydrate-binding module family 11 (CBM11) is found in a number of bacterial

cellulases Cellulase (EC 3.2.1.4; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysacchar ...

. One example is the CBM11 of Clostridium thermocellum Cel26A-Cel5E, this domain has been shown to bind both β-1,4-glucan and β-1,3-1,4-mixed linked glucans. CBM11 has beta-sandwich structure with a concave side forming a substrate-binding cleft.

CBM12

Carbohydrate-binding module family 12 (CBM12) comprises two

beta-sheet The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...

s, consisting of two and three antiparallel beta strands respectively. It binds chitin via the aromatic rings of

residues. CBM5 and CBM12 are distantly related.

CBM14

Carbohydrate-binding module family 14 (CBM14) is also known as the peritrophin-A domain. It is found in

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

binding proteins, particularly the

peritrophic matrix The peritrophic matrix (from the prefix ''peri-'', meaning around, and ''-trophic'', referring to nutrition(food)) or peritrophic membrane is a semi-permeable, non-cellular structure which surrounds the food Bolus (digestion), bolus in an organism' ...

proteins of insects and animal

chitinase Chitinases (EC 3.2.1.14, chitodextrinase, 1,4-β-poly-N-acetylglucosaminidase, poly-β-glucosaminidase, β-1,4-poly-N-acetyl glucosamidinase, poly ,4-(N-acetyl-β-D-glucosaminide)glycanohydrolase, (1→4)-2-acetamido-2-deoxy-β-D-glucan glycano ...

s. Copies of the domain are also found in some

baculoviruses ''Baculoviridae'' is a family of viruses. Arthropods, among the most studied being Lepidoptera, Hymenoptera and Diptera, serve as natural hosts. Currently, 85 species are placed in this family, assigned to four genera. Baculoviruses are kno ...

. It is an

extracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions ...

domain that contains six conserved

s that probably form three

disulfide bridges In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

. Chitin binding has been demonstrated for a protein containing only two of these domains.

CBM15

Carbohydrate-binding module family 15 (CBM15), found in bacterial enzymes, has been shown to bind to

xylan Xylan (; ) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abundant ...

and xylooligosaccharides. It has a beta-jelly roll fold, with a groove on the concave surface of one of the

CBM17

Carbohydrate-binding module family 17 (CBM17) appears to have a very shallow binding cleft that may be more accessible to cellulose

chain A chain is a serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression but linear, rigid, and load-bearing in tension. A c ...

s in non-crystalline cellulose than the deeper binding clefts of family 4 CBMs. Sequence and structural conservation in families CBM17 and CBM28 suggests that they have

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

through

gene duplication Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. ...

and subsequent divergence. CBM17 does not compete with CBM28 modules when binding to non-crystalline cellulose. Different CBMs have been shown to bind to different sites in amorphous cellulose, CBM17 and CBM28 recognise distinct non-overlapping sites in amorphous cellulose.

CBM18

Carbohydrate-binding module family 18 (CBM18) (also known as chitin binding 1 or chitin recognition protein) is found in a number of

and

s that

bind BIND () is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named (pronounced ''name-dee'': , short for ''name daemon''), performs both of the main DNS server roles, acting as an authoritative n ...

N-acetylglucosamine ''N''-Acetylglucosamine (GlcNAc) is an amide derivative of the monosaccharide glucose. It is a secondary amide between glucosamine and acetic acid. It is significant in several biological systems. It is part of a biopolymer in the bacterial ...

(e.g.

solanaceous The Solanaceae , or nightshades, are a family of flowering plants that ranges from annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal plants, spices, weeds, and orna ...

lectins Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in rec ...

of tomato and potato, plant endochitinases, the wound-induced proteins: hevein, win1 and win2, and the ''

Kluyveromyces lactis ''Kluyveromyces lactis'' is a ''Kluyveromyces'' yeast commonly used for genetic studies and industrial applications. Its name comes from the ability to assimilate lactose and convert it into lactic acid. ''Kluyveromyces lactis'' (formerly ''Sa ...

'' killer

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...

alpha subunit). The domain may occur in one or more copies and is thought to be involved in recognition or binding of

subunits. In chitinases, as well as in the

potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern Unit ...

wound-induced proteins, this 43-residue domain directly follows the signal sequence and is therefore at the N terminus of the mature protein; in the killer toxin alpha subunit it is located in the central section of the protein.

CBM19

Carbohydrate-binding module family 19 (CBM19), found in fungal

s, binds

CBM20

Carbohydrate-binding module family 20 (CBM20) binds to

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

CBM21

Carbohydrate-binding module family 21 (CBM21), found in many

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

proteins involved in

glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body. Glycogen functions as one o ...

metabolism, binds to glycogen.

CBM25

Carbohydrate-binding module family 25 (CBM25) binds alpha-glucooligosaccharides, particularly those containing alpha-1,6 linkages, and granular starch.

CBM27

Carbohydrate-binding module family 27 (CBM27) binds to beta-1,4-mannooligosaccharides,

carob The carob ( ; ''Ceratonia siliqua'') is a flowering evergreen tree or shrub in the Caesalpinioideae sub-family of the legume family, Fabaceae. It is widely cultivated for its edible fruit pods, and as an ornamental tree in gardens and landscap ...

galactomannan Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups, more specifically, a (1-4)-linked beta-D-mannopyranose backbone with branchpoints from their 6-positions linked to alpha-D-galactose, (i.e. 1-6-linked ...

, and

konjac Konjac (or konjak, ) is a common name of the East and Southeast Asian plant ''Amorphophallus konjac'' ( syn. ''A. rivieri''), which has an edible corm (bulbo-tuber). It is also known as konjaku, konnyaku potato, devil's tongue, voodoo lily, sn ...

glucomannan, but not to cellulose (insoluble and soluble) or soluble birchwood xylan. CBM27 adopts a beta sandwich structure comprising 13

beta strand The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a gen ...

s with a single, small

alpha-helix The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...

and a single metal

atom Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, and ...

CBM28

Carbohydrate-binding module family 28 (CBM28) does not compete with CBM17 modules when binding to non-crystalline cellulose. Different CBMs have been shown to bind to different sirtes in amorphous cellulose, CBM17 and CBM28 recognise distinct non-overlapping sites in amorphous cellulose. CBM28 has a "beta-jelly roll" topology, which is similar in structure to the CBM17 domains. Sequence and structural conservation in families CBM17 and CBM28 suggests that they have

through

and subsequent divergence.

CBM32

Carbohydrate-binding module family 32 (CBM32) binds to diverse substrates, ranging from plant cell wall polysaccharides to complex glycans. The module has so far been found in microorganisms, including archea, eubacteria and fungi. CBM32 adopts a beta-sandwich fold and has a bound metal atom, most often observed to be calcium.Ficko-Blean, Elizabeth; Boraston, Alisdair
"Carbohydrate Binding Module Family 32"CAZypedia
4 May 2017. CBM32 modules are associated with catalytic modules such as sialidases, B-N-acetylglucosaminidases, α-N-acetylglucosaminidases, mannanases and galactose oxidases.

CBM33

Carbohydrate-binding module family 33 (CBM33) is a chitin-binding domain. It has a budded fibronectin type III fold consisting of two beta-sheets, arranged as a beta-sheet sandwich and a bud consisting of three short helices, located between beta-strands 1 and 2. It binds chitin via conserved polar amino acids. This domain is found in isolation in baculoviral spheroidin and spindolin proteins.

CBM48

Carbohydrate-binding module family 48 (CBM48) is often found in enzymes containing

glycosyl hydrolase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (c ...

family 13 catalytic domains. It is found in a range of

that act on branched substrates i.e. isoamylase,

pullulanase Pullulanase (, ''limit dextrinase'', ''amylopectin 6-glucanohydrolase'', ''bacterial debranching enzyme'', ''debranching enzyme'', ''alpha-dextrin endo-1,6-alpha-glucosidase'', ''R-enzyme'', ''pullulan alpha-1,6-glucanohydrolase'') is a specific ki ...

and branching enzyme. Isoamylase hydrolyses 1,6-alpha-D-glucosidic branch linkages in glycogen,

amylopectin Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Plants store starch within specialized organelles called amylopl ...

and

dextrin Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds. Dextrins can be produced from ...

; 1,4-alpha-glucan branching enzyme functions in the formation of 1,6-glucosidic linkages of glycogen; and pullulanase is a starch-debranching enzyme. CBM48 binds glycogen.

CBM49

Carbohydrate-binding module family 49 (CBM49) is found at the C-terminal of cellulases and ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

'' binding studies have shown it to binds to crystalline cellulose.

References

External links

CAZy Carbohydrate binding modules
{{InterPro content, IPR001002 Protein domains