| proto-oncogenes | Normal cellular genes homologous to viral oncogenes. The products of proto-oncogenes are important regulators of biological processes and appear to be involved in the events that serve to maintain the ordered procession through the cell cycle. Proto-oncogenes have names of the form c-onc. (12 Dec 1998) |
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| protoactinium | <chemical> Protactinium. A radioactive element of the actinide group of metals. It has the atomic symbol pa, atomic number 91, and atomic weight 231. It decays by alpha-emission. Chemical name: Protactinium (12 Dec 1998) |
| protoalbumose | Intermediate products of protein digestion, derived from hemialbumose; soluble in water and not coagulable by heat, but precipitated by ammonium sulfate, cupric sulfate, and sodium chloride. Synonym: protoalbumose. (05 Mar 2000) |
| protoalkaloid | A biogenic amine serving as a precursor of an alkaloid. (05 Mar 2000) |
| protobe | F. D'Herelle's term for bacteriophage. Origin: proto-+ G. Bios, life (05 Mar 2000) |
| protobiology | The study of bacteriophages. Synonym: protobiology. (05 Mar 2000) |
| protocatechuate 2,3-dioxygenase | <enzyme> From bacillus macerans; catalyses the conversion of protocatechuate to alpha-hydroxy-delta-carboxymuconic saemialdehyde in the presence of oxygen Registry number: EC 1.13.11.- (26 Jun 1999) |
| protocatechuate-3,4-dioxygenase | <enzyme> An enzyme that catalyses the oxidation of protocatechuate to 3-carboxy-cis-cis-muconate in the presence of molecular oxygen. It contains ferric ion. Chemical name: Protocatechuate:oxygen 3,4-oxidoreductase (decyclizing) Registry number: EC 1.13.11.3 (12 Dec 1998) |
| protocatechuic | <chemistry> Pertaining to, derived from, or designating, an organic acid which is obtained as a white crystalline substance from catechin, asafetida, oil of cloves, etc, and by distillation itself yields pyrocatechin. Source: Websters Dictionary (01 Mar 1998) |
| protocatechuic acid | 3,4-Dihydroxybenzoic acid; 4-carboxycatechol;oxidation product of epinephrine. (05 Mar 2000) |
| protocercal | <zoology> Having a caudal fin extending around the end of the vertebral column, like that which is first formed in the embryo of fishes; diphycercal. Origin: Proto- + Gr. The tail. Source: Websters Dictionary (01 Mar 1998) |
| protochlorophyllide | <plant biology> Precursor of chlorophyll, found in proplastids and etioplasts. Lacks the phytol side chain of chlorophyll. (18 Nov 1997) |
| protochordal knot | A local thickening of the blastoderm at the cephalic end of the primitive streak of the embryo. Synonym: Hensen's knot, Hensen's node, Hubrecht's protochordal knot, primitive knot, protochordal knot. (05 Mar 2000) |
| protococcus | <botany> A genus of minute unicellular algae including the red snow plant (Protococcus nivalis). Origin: NL. See Proto-, and Coccus. Source: Websters Dictionary (01 Mar 1998) |
| protocol | A formula, a treatment recipe. (16 Dec 1997) |