| acid | <chemical, chemistry> A fundamental category of many compounds whose water-based solutions have a sour taste, turn blue litmus paper red and can combine with metals to form salts. They are chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Specific types of acids include: Arrhenius acid: any chemical that increases the number of free hydrogen ions (H+) when added to a water-based solution. The more free hydrogens produced, the stronger the acid. Bronsted or Bronsted-Lowry acid: any chemical that acts as a proton donor in a chemical reaction. Lewis acid: any chemical that accepts two electrons to form a covalent bond during a chemical reaction. (13 Nov 1997) |
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| acid agglutination | The clumping together of certain microorganisms at high hydrogen ion concentration. (05 Mar 2000) |
| acid anhydride hydrolases | <enzyme> A group of enzymes that catalyze the hydrolysis of diphosphate bonds in compounds such as nucleoside di- and tri-phosphates, and sulfonyl-containing anhydrides such as adenylylsulfate. (enzyme nomenclature, 1992). Registry number: EC 3.6 (12 Dec 1998) |
| acid-ash diet | A diet consisting mainly of fruits, vegetables, and milk (with minimal amounts of meat, fish, eggs, cheese, and cereals), which, when catabolised, leave an alkaline residue to be excreted in the urine. Synonym: acid-ash diet, basic diet. (05 Mar 2000) |
| acid-base balance | The normal balance between acid and base in the blood plasma, expressed in the hydrogen ion concentration or pH, resulting from the relative amounts of acidic and basic materials ingested and produced by body metabolism, compared to the relative amounts of acidic and basic materials excreted from the body and consumed by body metabolism; the normal state of acid-base balance is not one of neutrality, with equal concentrations of hydrogen and hydroxyl ions, but a more alkaline state with a certain excess of hydroxyl ions. Synonym: acid-base equilibrium. (05 Mar 2000) |
| acid-base equilibrium | A condition in which the net rate of acid or alkali production by the body is balanced by the net rate of acid or alkali excretion from the body, resulting in a stable concentration of hydrogen ions in the body fluids. (12 Dec 1998) |
| acid-base imbalance | Disturbances in the acid-base equilibrium of the body. (12 Dec 1998) |
| acid carboxypeptidase | <enzyme> Carboxypeptidase z (scpz gene product) isolated from absidia zychae Registry number: EC 3.4.16.1 Synonym: carboxypeptidase w, carboxypeptidase yscy, carboxypeptidase cpd-s3, ybr1015 gene product, carboxypeptidase z, scpz gene product (26 Jun 1999) |
| acid cell | One of the cell's of the gastric glands; it lies upon the basement membrane, covered by the chief cell's, and secretes hydrochloric acid that reaches the lumen of the gland through fine intracellular and intercellular canals (canaliculi). Synonym: acid cell, oxyntic cell. (05 Mar 2000) |
| acid cholesterol ester synthetase | <enzyme> Aortal enzyme, does not require exogenous ATP or CoA; reverse reaction of cholesterol esterase Registry number: EC 3.1.1.- Synonym: cholesterol ester synthetase (26 Jun 1999) |
| acid-citrate-dextrose | A citrate anticoagulant used for the collection and preservation of whole blood. It has largely been replaced by newer coagulants (CPD, Adsol) that allow for longer shelf life for blood and blood products. Acronym: ACD (05 Mar 2000) |
| acid deoxyribonuclease | An endonuclease that cleaves both strands of native DNA (as well as single-stranded DNA) to produce a mixture of oligodeoxynucleotides, each ending in a 3'-phosphate. Synonym: acid deoxyribonuclease. (05 Mar 2000) |
| acid dextran | The product of acid and heat treatment of dextran. (05 Mar 2000) |
| acid dextrin | The product of acid and heat treatment of dextrin. (05 Mar 2000) |
| acid dissociation constant | <chemistry> This is the equilibrium constant for the breaking apart of a weak acid into its hydrogen and conjugate base in a water solution. (09 Oct 1997) |