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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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glutaminate (gloo-tam′in-at)
The anion form of glutamine.

glutamine (Gln, Q) (gloo′ta-men, -ta-min, gloo-tam′in)
The δ-amide of glutamic acid, derived by oxidation from proline in the liver or by the combination of glutamic acid with ammonia; the l-isomer is present in proteins and in blood and other tissues, and is an important source of urinary ammonia, being broken down in the kidney by the action of the enzyme glutaminase; nonenzymatically, it is converted to 5-oxoproline. g. aminotransferase an enzyme that reversibly reacts l-g. with α-ketoglutarate to produce α-ketoglutaramate and l-glutamate; α-ketoglutaramate is elevated in certain cases of hepatocoma. SYN: g. transaminase. g. synthetase an enzyme that catalyzes the reaction of l-glutamic acid, ammonia, and ATP to g., ADP, and orthophosphate; one of the few known mammalian enzymes that uses ammonium ion as a substrate under physiological conditions. g. transaminase SYN: g. aminotransferase.

glutaminyl (Gln, Glx, Q) (gloo-tam′i-nil)
The acyl radical of glutamine.

glutamoyl (gloo-tam′o-il)
The radical of glutamic acid from which both α- and δ-hydroxyl groups have been removed.

glutamyl (E, Glu, Glx) (gloo-tam′il, gloo′ta-mil)
The radical of glutamic acid from which either the α- or the δ-hydroxyl group has been removed.

γ-glutamyl carboxylase
An enzyme that catalyzes the formation of γ-carboxyglutamyl residues in many proteins, several appearing in the blood clotting cascade.

γ-glutamylcysteine (gloo′ta-mil-sis′te-in)
A necessary precursor in the biosynthesis of glutathione; contains an isopeptide rather than a eupeptide bond. γ-glutamylcysteine synthetase an enzyme that catalyzes the first step in glutathione biosynthesis, reacting l-glutamate, l-cysteine, and ATP to form γ-glutamylcysteine, ADP, and orthophosphate; inhibited by thiols such as glutathione.

γ-glutamyl hydrolase
An enzyme cleaving l-glutamyl residues from pteridine oligoglutamates; used in certain antitumor treatments. SYN: carboxypeptidase G, γ-glutamate (glutamate γ-) carboxypeptidase.

γ-glutamyltransferase (gloo-tam′il-trans′fer-as)
An enzyme that catalyzes the transfer of a γ-glutamyl group from a γ-glutamyl peptide (usually glutathione) to another peptide, certain amino acids, or water; a deficiency of this enzyme will result in glutathionuria. SYN: γ-glutamyl transpeptidase.

γ-glutamyl transpeptidase
SYN: γ-glutamyltransferase.

glutaral (gloo′ta-ral)
SYN: glutaraldehyde.

glutaraldehyde (gloo-ta-ral′de-hid)
A dialdehyde used as a fixative for electron microscopy, especially for nuclear morphology and for localization of enzyme activity; also used as a germicidal agent for disinfection and sterilization of instruments or equipment that cannot be heat sterilized. SYN: glutaral.

glutaric acid (gloo-tar′ik)
Pentanedioic acid;an intermediate in tryptophan catabolism; accumulates in glutaric acidemia.

glutaryl-CoA (gloo′ta-ril)
The mono thiol ester of coenzyme A and glutaric acid; an intermediate in l-lysine and l-tryptophan catabolism. glutaryl-CoA dehydrogenase an enzyme that catalyzes the reaction of glutaryl-CoA with an acceptor to form crotonoyl-CoA, CO2, and the reduced acceptor; a deficiency of this enzyme will lead to either glutaric acidemia type I or hyperoxaluria type II. glutaryl-CoA synthetase an enzyme similar to acyl-CoA synthetase, but which splits ATP, GTP, or ITP to the nucleoside diphosphate and orthophosphate in acting on glutarate, thus forming glutaryl-Coa.

glutathione (GSH) (gloo-ta-thi′on)
A tripeptide of glycine, l-cysteine, and l-glutamate, with l-glutamate having an isopeptide bond with the amino moiety of l-cysteine. G. has a wide variety of roles in a cell; it is the most prevalent non-protein thiol. G. disulfide (GSSG) consists of two glutathiones linked via a disulfide bridge; the term oxidized g. for GSSG should be avoided since it includes the sulfones and sulfoxides. The term reduced g. is not necessary since g. is the thiol form. A deficiency of g. can cause hemolysis with oxidative stress. It is also used in the course of intermediary metabolism as a donor of thiol (SH) groups and is essential for detoxification of acetaminophen. SEE ALSO: oxidized g., reduced g., g. reductase. oxidized g. 1. g. acting in cells as a hydrogen acceptor; reduced by g. reductase; g. disulfide; 2. sulfones or sulfoxides of g. or g. disulfide. g. peroxidase an enzyme that catalyzes the reaction of two glutathiones with H2O2 forming GSSG and two water molecules; a crucial enzyme in hydrogen peroxide detoxification. reduced g. g. acting as a hydrogen donor; g.. g. reductase an enzyme that catalyzes the reaction of GSSG with NADH (or NADPH) forming two glutathiones and NAD+ (or NADP+); involved in many redox reactions; a deficiency can cause hemolysis with oxidative stress. g. synthetase an enzyme that catalyzes the formation of g., ADP, and orthophosphate from γ-glutamylcysteine, ATP, and glycine; a deficiency will lead to metabolic acidosis and progressive brain dysfunction. g. S-transferase a class of enzymes that catalyze the reaction of g. with an acceptor molecule ( E.G., an arene oxide) to form an S-substituted g.; a key step in detoxification of many substances; start of the mercapturic acid pathway. SYN: ligandin.

glutathionuria (gloo-ta-thi′o-nur-e-a)
Elevated glutathione and/or glutathione disulfide levels in the urine.

gluteal (gloo′te-al)
Relating to the buttocks. [G. gloutos, buttock]

glutelins (gloo′te-linz)
A class of simple proteins occurring in the seeds of grain; soluble in dilute acids and bases, but not in neutral solutions ( e.g., glutenin from wheat and orycenin in rice). They have glutamin-rich domains and serve as storage proteins.

gluten (gloo′ten)
The insoluble protein (prolamines) constituent of wheat and other grains; a mixture of gliadin, glutenin, prolamins, and other proteins; the presence of g. allows flour to rise. SYN: wheat gum. [L. g., glue] g. casein a protein resembling casein, present in g..

glutenin (gloo′te-nin)
Any glutelin in the endosperm of wheat seeds; believed to be responsible for the viscoelastic properties of wheat dough.

gluteofemoral (gloo′te-o-fem′o-ral)
Relating to the buttock and the thigh.

gluteoinguinal (gloo′te-o-ing′gwi-nal)
Relating to the buttock and the groin.

glutethimide (gloo-teth′i-mid)
A central nervous system depressant used as a hypnotic in simple insomnia and formerly as a daytime sedative.

gluteus (gloo-te′us)
See g. maximus (muscle), g. medius (muscle), g. minimus (muscle).

glutinoid (gloo′ti-noyd)
SYN: albuminoid (3) .

glutinous (gloo′tin-us)
Sticky.

glutitis (gloo-ti′tis)
Inflammation of the muscles of the buttock. [G. gloutos, buttock, + -itis, inflammation]

Glx
Symbol for glutamyl (Glu), glutaminyl (Gln), and/or any substance that would yield glutamate upon acid hydrolysis of a peptide ( e.g., 5-oxoproline, 4-carboxyglutamate) to denote the uncertainty between them.

Gly
Symbol for glycine or its acyl radical, glycyl.

glyburide (gli′bu-rid)
An oral hypoglycemic drug used in the treatment of type II diabetes.

glycal (gli′kal)
An unsaturated sugar derivative in which the adjacent hydroxyl groups are removed, one of which is that upon the carbon-1 of the aldose (or carbon-2 of the ketose), yielding a CH&dbond;CH between these two positions. SYN: glucal.

glycan (gli′kan)
SYN: polysaccharide. SEE ALSO: heteroglycan, homoglycan.

glycanohydrolases (gli′kan-o-hi′dro-la-sez) [EC 3.2.1.x]
Hydrolases acting on glycans; e.g., chitinase, hyaluronoglucosidase.

glycate (gli′kat)
The product of the nonenzymic reaction between a sugar and the free amino group(s) of proteins in which it is not known if the sugar is attached by a glycosyl or a glycoside linkage, or has formed a Schiff base.

glycation (gli-ka′shun)
The nonenzymic reaction that forms a glycate.

glycemia (gli-se′me-a)
The presence of glucose in the blood. [G. glykys, sweet, + haima, blood]

glyceraldehyde (glis-er-al′de-hid)
A triose and the simplest optically active aldose; the dextrorotatory isomer is taken as the structural reference point for all d compounds, the levorotatory isomer for all l compounds. SYN: glyceric aldehyde.

glyceraldehyde 3-phosphate
An intermediate in the glycolytic breakdown of d-glucose; one of the products of the splitting of fructose 1,6-bisphosphate under the catalytic influence of fructose-bisphosphate aldolase.

glyceric acid (gli-ser′ik, glis′er-ik)
The fatty acid analog of glycerol; occurs particularly in the form of phosphorylated derivatives as an intermediate in glycolysis.

glyceric aldehyde
SYN: glyceraldehyde.

glyceridases (glis′er-i-das-ez)
General term for enzymes catalyzing the hydrolysis of glycerol esters (glycerides); e.g., triacylglycerol lipase.

glyceride (glis′er-id, -id)
An ester of glycerol. The term is usually used in combination with phospho- (phosphoglyceride). The use of mono-, di-, and triglyceride is being replaced by the more precise terms mono-, di-, and triacylglycerol, respectively. mixed glycerides glycerides which, on hydrolysis, yield more than one variety of fatty acid.

glycerin (glis′er-in)
SYN: glycerol. g. jelly SYN: glycerinated gelatin.

glycerite (glis′er-it)
1. SYN: glycerol. 2. A pharmaceutical preparation made by triturating the active medicinal substance with glycerol. starch g. a preparation containing 100 g of starch, 2 g of benzoic acid, 200 ml of purified water, and 700 g of glycerin in each 1000 g; a topical emollient. tannic acid g. g. of tannin, containing tannic acid, sodium citrate, exsiccated sodium sulfite, and glycerin; an astringent.

glycerogelatin (glis′er-o-jel′a-tin)
SYN: glycerinated gelatin.

glycerokinase (glis′er-o-ki′nas)
SYN: glycerol kinase.

glycerol (glis′er-ol)
A sweet viscous fluid obtained by the saponification of fats and fixed oils; used as a solvent, as a skin emollient, by injection or in the form of suppository for constipation, and as a vehicle and sweetening agent. SYN: 1,2,3-propanetriol, glycerin, glycerite (1) , glyceryl alcohol. iodinated g. a form of organically bound iodine which liberates iodine systemically. Has been used as a medicinal source of iodine and as an expectorant in place of inorganic iodides such as potassium iodide. SYN: iodopropylidene g., organidin. g. kinase an enzyme that catalyzes a reaction between ATP and g. to yield sn-g. 3-phosphate and ADP; in adipose tissue, the first and rate-limiting step in the synthesis of triacylglycerols; deficiency results in the disruption of adrenal, muscle, and/or liver and brain function. SYN: glycerokinase. g. phosphate the anion of a phosphoric ester of g.; the 3-derivative is the central component of phosphatidates (R-g. 3-phosphate). SYN: glycerophosphate.

glycerol-3-phosphate acyltransferase
An enzyme that participates in phospholipid biosynthesis, catalyzing the transfer of an acyl group from a fatty acyl-CoA to sn-glycerol-3-phosphate, producing coenzyme A and lysophosphatidic acid.

glycerol-3-phosphate dehydrogenase (NAD+)
α-Glycerol phosphate dehydrogenase; 3-phosphoglycerol dehydrogenase;a flavoenzyme that catalyzes the interconversion of dihydroxyacetone phosphate and sn-glycerol 3-phosphate, with the participation of NAD+; its action provides the glycerol moiety from carbohydrate during lipogenesis.

glycerone
The IUPAC recommended name for dihydroxyacetone.

glycerophosphate (glis′er-o-fos′fat)
SYN: glycerol phosphate.

glycerophosphocholine (glis′er-o-fos-fo-ko′len)
A component of phosphatidylcholines (lecithins), in which the two OH's of g. are esterified with fatty acids. SYN: glycerophosphorylcholine.

glycerophosphoric acid (glis′er-o-fos-for′ik)
A phosphoric ester of glycerol. SEE ALSO: glycerol phosphate.

glycerophosphorylcholine (glis′er-o-fos′for-il-ko′len)
SYN: glycerophosphocholine.

glycerulose (glis-er′ul-ose)
SYN: dihydroxyacetone.

glyceryl (glis′er-il)
1. The trivalent radical, C3H53−, of glycerol; often used in error for glycero- or glycerol. 2. Any group derived from glycerol by removing one or more of the hydroxyl groups. g. alcohol SYN: glycerol. g. borate SYN: boroglycerin. g. guaiacolate SYN: guaifenesin. g. iodide an organic form of iodine which slowly liberates iodine in the body after oral administration. Used primarily as an expectorant/mucolytic. SYN: 3-iodo-1,2-propanediol, γ-iodopropyleneglycol. g. monostearate the ester of glycerol and one molecule of stearic acid; used in the manufacture of cosmetic creams and dermatologic preparations. g. triacetate SYN: triacetin. g. tributyrate SYN: tributyrin. g. tricaprate SYN: caprin. g. trinitrate SYN: nitroglycerin.

glycinamide ribonucleotide (gli-sin′a-mid)
See glycineamide ribonucleotide.

glycinate (gli′sin-at)
1. A salt of glycine. 2. Glycine anion.

glycine (G, Gly) (gli′sen)
The simplest amino acid; a major component of gelatin and silk fibroin; used as a nutrient and dietary supplement, and in solution for irrigation; used in the treatment of sweaty feet syndrome. SYN: gelatin sugar. g. acyltransferase an enzyme catalyzing the reversible transfer of an acyl group from acyl-CoA to g., producing free coenzyme A and N-acylglycine; a step in a detoxification pathway. g. amidinotransferase an enzyme catalyzing the transfer of an amidine group from l-arginine to g., forming guanidinoacetate and l-ornithine; an important reaction in creatine biosynthesis; it can also act on canavanine. SYN: g. transamidinase. g. betaine SYN: betaine. g. cleavage complex a complex of several proteins that catalyze the reversible reaction of g. with tetrahydrofolate to produce CO2, NH3, and N5,N10-methylenetetrahydrofolate; a deficiency of this enzyme (or one of its subunits) will result in nonketotic hyperglycinemia. SYN: g. synthase. g. dehydrogenases enzymes that catalyze the conversion of g. to glyoxylate and ammonia, using either NAD+ or ferricytochrome c. g. synthase SYN: g. cleavage complex. g. transamidinase SYN: g. amidinotransferase.

glycineamide ribonucleotide, glycinamide ribonucleotide (gli′sin-a-mid, gli-sin′a-mid)
An intermediate in purine biosynthesis, in which the amide nitrogen of glycineamide is linked to the C-1 of a ribosyl moiety.

glycinin (gli-sen′in)
The chief protein of soybeans; a globulin that is structurally similar to arachin, edestin, and excelsin.

glycinium (gli-sen-e-um)
Glycine cation.

glycinuria (gli-si-noo′re-a)
The excretion of glycine in the urine. [glycine + G. ouron, urine] familial g. [MIM*138500] a metabolic disorder believed to be due to defective renal glycine reabsorption; it may or may not be accompanied by oxalate urolithiasis; may be the heterozygous state of iminoglycinuria; autosomal dominant inheritance.

glyco-
Combining form denoting relationship to sugars ( e.g., glycogen) or to glycine ( e.g., glycocholate). SEE ALSO: gluco-. [G. glykys, sweet]

glycobiarsol (gli-ko-bi′ar-sol)
A pentavalent arsenical containing bismuth; used in the treatment of milder forms of intestinal amebiasis or as subsequent therapy.

glycocalyx (gli-ko-ka′liks)
A PAS-positive filamentous coating on the apical surface of certain epithelial cells, composed of carbohydrate moieties of proteins that protrude from the free surface of the plasma membrane. [glyco- + G. kalyx, husk, shell]




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