1-Aminocyclopropane-1-carboxylic acid (ACC) is a disubstituted cyclic α-
amino acid in which a
cyclopropane
Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself ...
ring is fused to the C atom of the amino acid. It is a white solid. Many cyclopropane-substituted amino acids are known, but this one occurs naturally. Like glycine, but unlike most α-amino acids, ACC is not chiral.
Biochemistry
ACC is the precursor to
the plant hormone ethylene.
It is synthesized by the enzyme
ACC synthase () from
methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical ro ...
and converted to ethylene by
ACC oxidase ().
ACC also exhibits ethylene-independent signaling that plays a critical role in
pollination and seed production by activating proteins similar to those involved in nervous system responses in humans and animals. More specifically, ACC signaling promotes secretion of the
pollen tube
A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells fro ...
chemoattractant
Chemotaxis (from '' chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemical ...
LURE1.2 in
ovular sporophytic
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygote pr ...
tissue thus enhancing pollen tube attraction. Additionally, ACC activates
Ca2+-containing
ion currents via
glutamate receptor-like (GLR) channels in root
protoplasts.
ACC can be used by soil
microorganisms
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 ...
(both
bacteria and
fungi) as a source of
nitrogen and
carbon.
As such, using ACC to incubate soils has been proven to induce the gene abundance encoding ACC-
deaminases, which may have positive consequences on
plant growth and
stress tolerance.
ACC has also been extracted from
kelp.
ACC is also an exogenous
partial agonist of the
mammalian NMDA receptor
The ''N''-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA rece ...
.
In 2019, the
United States Environmental Protection Agency issued notice of an application for an
experimental use permit to be issued for use of ACC as a
pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
.
References
Cyclic amino acids
Cyclopropanes
NMDA receptor agonists
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