|
Orotidine-5'-phosphate Decarboxylase
The enzyme Uridine monophosphate synthase (, UMPS) (orotate phosphoribosyl transferase and orotidine-5'-decarboxylase) catalyses the formation of uridine monophosphate (UMP), an energy-carrying molecule in many important biosynthetic pathways. In humans, the gene that codes for this enzyme is located on the long arm of chromosome 3 (3q13). Structure and function This bifunctional enzyme has two main domains, an orotate phosphoribosyltransferase (OPRTase, ) subunit and an orotidine-5’-phosphate decarboxylase (ODCase, ) subunit. These two sites catalyze the last two steps of the de novo uridine monophosphate (UMP) biosynthetic pathway. After addition of ribose-P to orotate by OPRTase to form orotidine-5’-monophosphate (OMP), OMP is decarboxylated to form uridine monophosphate by ODCase. In microorganisms, these two domains are separate proteins, but, in multicellular eukaryotes, the two catalytic sites are expressed on a single protein, uridine monophosphate synthase. UMPS exi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uridine Monophosphate
Uridine monophosphate (UMP), also known as 5′-uridylic acid (conjugate base uridylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside uridine. UMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase uracil; hence, it is a ribonucleotide monophosphate. As a substituent or radical its name takes the form of the prefix uridylyl-. The deoxy form is abbreviated dUMP. Covalent attachment of UMP (e.g. to a protein such as adenylyltransferase) is called uridylylation (or sometimes uridylation). Biosynthesis Uridine monophosphate is formed from Orotidine 5'-monophosphate (orotidylic acid) in a decarboxylation reaction catalyzed by the enzyme orotidylate decarboxylase. Uncatalyzed, the decarboxylation reaction is extremely slow (estimated to occur on average one time per 78 million years). Adequately catalyzed, the reaction takes place once per second, an increase of 1017-fold. In humans, the orotidyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 3
Chromosome 3 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 3 spans almost 200 million base pairs (the building material of DNA) and represents about 6.5 percent of the total DNA in cells. Genes Number of genes The following are some of the gene count estimates of human chromosome 3. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes. List of genes The following is a partial list of genes on human chromosome 3. For complete list, see the link in the infobox on the right. p-arm Partial list of the genes located on p-arm (short arm) of human chromosome 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentation Coefficient
The sedimentation coefficient () of a particle characterizes its sedimentation during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied acceleration causing the sedimentation. : s = \frac The sedimentation speed is also the terminal velocity. It is constant because the force applied to a particle by gravity or by a centrifuge (typically in multiples of tens of thousands of gravities in an ultracentrifuge) is balanced by the viscous resistance (or "drag") of the fluid (normally water) through which the particle is moving. The applied acceleration can be either the gravitational acceleration , or more commonly the centrifugal acceleration . In the latter case, is the angular velocity of the rotor and is the distance of a particle to the rotor axis (radius). The viscous resistance for a spherical particle is given by Stokes' law: , where is the viscosity of the medium, is the radius of the particle and is the velocity of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OPRTase In Complex With OMP
Orotate phosphoribosyltransferase (OPRTase) or orotic acid phosphoribosyltransferase is an enzyme involved in pyrimidine biosynthesis. It catalyzes the formation of orotidine 5'-monophosphate (OMP) from orotate and phosphoribosyl pyrophosphate. In yeast and bacteria, orotate phosphoribosyltransferase is an independent enzyme with a unique gene coding for the protein, whereas in mammals and other multicellular organisms, the catalytic function is carried out by a domain of the bifunctional enzyme UMP synthase (UMPS). Biological background As OPRTase is part of a bifunctional complex UMP synthase in humans, the function and stability of this enzyme is not necessarily directly associated with disorders in the human body. It is however reasonable to believe that a dysfunction in one of the enzymes will cause a dysfunction of the whole enzyme. Defects in UMP synthase is associated with hypochromic anemia. In mammals, this bifunctional enzyme UMPS converts orotic acid into uridine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orotic Aciduria
Orotic aciduria (AKA hereditary orotic aciduria) is a disease caused by an enzyme deficiency resulting in a decreased ability to synthesize pyrimidines. It was the first described enzyme deficiency of the ''de novo'' pyrimidine synthesis pathway. Orotic aciduria is characterized by excessive excretion of orotic acid in urine because of the inability to convert orotic acid to UMP. It causes megaloblastic anemia and may be associated with mental and physical developmental delays. Signs and symptoms Patients typically present with excessive orotic acid in the urine, failure to thrive, developmental delay, and megaloblastic anemia which cannot be cured by administration of vitamin B12 or folic acid. Cause and genetics This autosomal recessive disorder is caused by a deficiency in the enzyme UMPS, a bifunctional protein that includes the enzyme activities of OPRT and ODC. In one study of three patients, UMPS activity ranged from 2-7% of normal levels. Two types of orotic acidur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosomal Recessive
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holstein Cattle
Holstein Friesians (often shortened to Holsteins in North America, while the term Friesians is often used in the UK and Ireland) are a breed of dairy cattle that originated in the Dutch provinces of North Holland and Friesland, and Schleswig-Holstein in Northern Germany. They are known as the world's highest-producing dairy animals. Dutch and German breeders developed the breed with the goal of producing animals that could most efficiently use grass, the area's most abundant resource, as their food. Over the centuries, the result was a high-producing, black-and-white dairy cow. The Holstein-Friesian is the most widespread cattle breed in the world; it is found in more than 150 countries. With the growth of the New World, a demand for milk developed in North America and South America, and dairy breeders in those regions at first imported their livestock from the Netherlands. However, after about 8,800 Friesians ( black pied German cows) had been imported, Europe stopped exporting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mycobacterium Tuberculosis
''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, and as a result, ''M. tuberculosis'' can appear weakly Gram-positive. Acid-fastness, Acid-fast stains such as Ziehl–Neelsen stain, Ziehl–Neelsen, or Fluorescence, fluorescent stains such as Auramine O, auramine are used instead to identify ''M. tuberculosis'' with a microscope. The physiology of ''M. tuberculosis'' is highly aerobic organism, aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, it infects the lungs. The most frequently used diagnostic methods for tuberculosis are the Mantoux test, tuberculin skin test, Acid-Fast Stain, acid-fast stain, Microbiological cultu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orotidine 5'-phosphate Decarboxylase
Orotidine 5'-phosphate decarboxylase (OMP decarboxylase) or orotidylate decarboxylase is an enzyme involved in pyrimidine biosynthesis. It catalyzes the decarboxylation of orotidine monophosphate (OMP) to form uridine monophosphate (UMP). The function of this enzyme is essential to the de novo biosynthesis of the pyrimidine nucleotides uridine triphosphate, cytidine triphosphate, and thymidine triphosphate. OMP decarboxylase has been a frequent target for scientific investigation because of its demonstrated extreme catalytic efficiency and its usefulness as a selection marker for yeast strain engineering. Catalysis OMP decarboxylase is known for being an extraordinarily efficient catalyst capable of accelerating the uncatalyzed reaction rate by a factor of 1017. To put this in perspective, the uncatalysed reaction which would take ''78 million years'' to convert half the reactants into products is accelerated to ''18 milliseconds'' when catalyzed by OMP decarboxylase. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orotate Phosphoribosyltransferase
Orotate phosphoribosyltransferase (OPRTase) or orotic acid phosphoribosyltransferase is an enzyme involved in pyrimidine biosynthesis. It catalyzes the formation of orotidine 5'-monophosphate (OMP) from orotate and phosphoribosyl pyrophosphate. In yeast and bacteria, orotate phosphoribosyltransferase is an independent enzyme with a unique gene coding for the protein, whereas in mammals and other multicellular organisms, the catalytic function is carried out by a domain of the bifunctional enzyme UMP synthase (UMPS). Biological background As OPRTase is part of a bifunctional complex UMP synthase in humans, the function and stability of this enzyme is not necessarily directly associated with disorders in the human body. It is however reasonable to believe that a dysfunction in one of the enzymes will cause a dysfunction of the whole enzyme. Defects in UMP synthase is associated with hypochromic anemia. In mammals, this bifunctional enzyme UMPS converts orotic acid into uridine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
