10,041 articles
AbrB family
AbrB family (InterPro IPR007820): bacterial transition state regulators exemplified by Bacillus subtilis AbrB, a 94-residue dimeric DNA-binding repressor-activator with a novel looped-hinge helix fold; homolog Abh regulates biofilm formation.
Abrin
Abrin is a highly toxic type II ribosome-inactivating protein from Abrus precatorius (rosary pea, jequirity bean) seeds, about 75 times more potent than ricin, with an estimated human fatal dose of 0.1-1 microgram/kg and no antidote.
Absence of vulva
Absence of vulva (ICD-11 LB40.0; ICD-10-CM Q52.71, congenital absence of vulva) is a rare birth defect in which external female genitalia are partially or completely absent, usually with other urogenital anomalies.
ACACA
ACACA (acetyl-CoA carboxylase alpha, ACC1) is the human 17q12 gene encoding the cytosolic, biotin-dependent enzyme catalyzing acetyl-CoA to malonyl-CoA, the rate-limiting step of fatty acid synthesis and a drug target for NASH, diabetes, and cancer.
ACAN
ACAN (aggrecan, MIM 155760) is a human gene on 15q26.1 encoding aggrecan, cartilage's most abundant proteoglycan. Heterozygous variants cause familial short stature, osteochondritis dissecans, and early osteoarthritis.
ACAT1
ACAT1 (acetyl-CoA acetyltransferase 1, also T2, MAT, THIL) is a human chromosome 11 gene encoding mitochondrial acetoacetyl-CoA thiolase (EC 2.3.1.9) for ketone body and isoleucine metabolism; its mutation causes beta-ketothiolase deficiency, and its symbol is confused with SOAT1.
Accelerated blood clearance phenomenon
The accelerated blood clearance phenomenon is the rapid immune-driven loss from circulation of a second dose of PEGylated nanocarriers, first described by Dams and colleagues in 2000.
Accessory secretory protein Asp5
Accessory secretory protein Asp5 (Asp5, formerly Orf6) is a Streptococcus gordonii membrane protein that, with SecY2 and Asp4, forms the accessory Sec translocon exporting serine-rich glycoproteins; distinct from Toxoplasma ASP5.
Acclimatization
Acclimatization is physiological adjustment to natural environmental stress such as heat, cold, or altitude hypoxia over days to weeks, distinct from lab-based acclimation and genetic adaptation, with NIOSH heat schedules and altitude responses.
Acetaldehyde dehydrogenase
Acetaldehyde dehydrogenase (ALDH), especially the mitochondrial ALDH2 isozyme, oxidizes toxic acetaldehyde from ethanol to acetate; ALDH2*2 (rs671) inactivates it, causing East Asian alcohol flushing and higher cancer risk.
Acetate/propionate kinase
Acetate/propionate kinase: acetate kinase (EC 2.7.2.1, AckA) and propionate kinase (EC 2.7.2.15, TdcD/PduW), ASKHA-superfamily bacterial enzymes phosphorylating short-chain carboxylates with ATP; pocket size (Val93/Ala88) sets substrate specificity; used for ATP regeneration.
Acetoacetate
Acetoacetate (3-oxobutanoate) is the anion of acetoacetic acid and one of three ketone bodies the liver produces from fatty acids during fasting, low-carbohydrate diets, and uncontrolled diabetes.
Acetoacetate decarboxylase
Acetoacetate decarboxylase (EC 4.1.1.4, adc) is a bacterial Schiff-base lyase converting acetoacetate to acetone and CO2 in Clostridium acetobutylicum ABE fermentation, famous for Lys115 pKa lowered to 6.0 by active-site desolvation.
Acetoacetic acid
Acetoacetic acid (acetoacetate, AcAc), a ketone body produced by liver β-oxidation of fatty acids; first ketone body formed, interconverted with β-hydroxybutyrate, decarboxylates to acetone, fuel and precursor in fasting and diabetic ketosis.
Acetoacetyl-CoA reductase
Acetoacetyl-CoA reductase (EC 1.1.1.36, PhaB/phbB) is an NADPH-dependent SDR enzyme reducing acetoacetyl-CoA to (R)-3-hydroxybutyryl-CoA, the second step of bacterial polyhydroxybutyrate biosynthesis, with NADH-dependent exceptions such as Allochromatium vinosum.
Acetyl esterase
Acetyl esterase (acetyl xylan esterase, EC 3.1.1.72): microbial carbohydrate esterase hydrolyzing acetyl ester bonds on xylan and hemicellulose, releasing acetic acid; families CE1–CE7, CE12, CE16.
Acetyl-CoA
Acetyl-CoA (acetyl coenzyme A), the thioester of coenzyme A and acetate, is the central two-carbon carrier in metabolism, feeding the citric acid cycle, supplying carbon for fatty acid and cholesterol synthesis, and donating acetyl groups for histone and protein acetylation.
Acetyl-CoA biotin carboxyl carrier
Acetyl-CoA biotin carboxyl carrier, known as biotin carboxyl carrier protein (BCCP), is a biotin-bearing protein domain that shuttles a carboxyl group between active sites of acetyl-CoA carboxylase, catalyzing the first committed step of fatty acid synthesis.
Acetyl-CoA carboxylase
Acetyl-CoA carboxylase (ACC, ACC1/ACC2, ACACA/ACACB) is the biotin-dependent, rate-limiting enzyme converting acetyl-CoA to malonyl-CoA in fatty acid synthesis, targeted by drugs for NASH, diabetes, and cancer and by ACCase-inhibiting herbicides.
Acetyl-S-ACP:malonate ACP transferase
Acetyl-S-ACP:malonate ACP transferase (EC 2.3.1.187; MdcA, MadA) is a bacterial family II ACP transferase that exchanges acetyl-ACP thioester for malonate, forming malonyl-ACP and acetate, the first step of malonate decarboxylation.
Acetylcarnitine
Acetylcarnitine, also known as acetyl-L-carnitine (ALC, also sold as ALCAR), is the acetic acid ester of carnitine that buffers excess acetyl-CoA in mitochondria during fatty-acid oxidation.
Acetylcholinesterase
Acetylcholinesterase (AChE, EC 3.1.1.7), also called acetylcholine hydrolase, is the serine hydrolase that hydrolyzes the neurotransmitter acetylcholine to choline and acetic acid at cholinergic synapses; its inhibition underlies Alzheimer's drugs and nerve agents like sarin.
Acetylene reduction assay
The acetylene reduction assay (ARA) estimates nitrogenase activity by incubating a sample with acetylene and measuring the ethylene formed by gas chromatography, a mainstay of nitrogen fixation research since the late 1960s.
Acetylglutamate kinase family
Acetylglutamate kinase (NAGK, EC 2.7.2.8, argB) family: AAK-family enzymes phosphorylating N-acetylglutamate in arginine biosynthesis; arginine feedback-inhibited, PII-regulated in phototrophs, absent in mammals.
Acetylornithine/Succinylornithine transaminase family
Acetylornithine/Succinylornithine transaminase family (InterPro IPR004636): PLP-dependent class-III aminotransferases (EC 2.6.1.11) such as ArgD and AstC that interconvert N-acetylornithine and N-acetylglutamate-5-semialdehyde in arginine biosynthesis and catabolism, with ArgD also serving as dapC in lysine synthesis.
Acetylxylan esterase
Acetylxylan esterase (acetyl xylan esterase, AXE, EC 3.1.1.72), a carbohydrate esterase removing O-acetyl groups from xylan at xylopyranosyl O-2/O-3; CE families 1-7 and 16, serine catalysis except metal-dependent CE4; used in pulp biobleaching and biofuel.
Achiasmate meiosis
Achiasmate meiosis (achiasmy): meiosis without chiasmata or crossovers, first seen in Drosophila males and Bombyx females; homologs segregate via backup tethers like Drosophila AHC and centromere pairing.
ACHN
ACHN (CVCL_1067, ATCC CRL-1611) is a human renal cell carcinoma cell line begun in 1979 from a pleural effusion of a 22-year-old man; genomically papillary, VHL wild type, NCI-60 member.
Achondroplasia
Achondroplasia (ACH, FGFR3-related achondroplasia) is the most common genetic cause of disproportionate short stature, caused by Gly380Arg FGFR3 gain-of-function variants; treated with vosoritide (Voxzogo) and navepegritide (Yuviwel).
Acid fungal protease
Acid fungal protease (AFP), an aspartic acid protease (E.C.3.4.23) from fungi such as Aspergillus and Trichoderma reesei, active at pH 3-4, used in cheese making, brewing, baking, and meat tenderization; GRAS as GRN 333.