Molecular cloning and sequence analysis of the cDNA for ancrod, a thrombin-like enzyme from the venom of Calloselasma rhodostoma.
The 1.54 kb cDNA for ancrod, a thrombin-like enzyme, was cloned from a lambda ZAP cDNA library derived from the venom glands of Calloselasma (Agkistrodon) rhodostoma. The cDNA sequence reveals that ancrod is synthesized as a pre-zymogen of 258 amino acids, including a putative secretory peptide of 18 amino acids and a proposed zymogen peptide of 6 amino-acid residues. The amino-acid sequence of the predicted active form of the enzyme exhibits a high degree of sequence similarity to those of mammalian serine proteases (trypsin and pancreatic kallikrein) and other thrombin-like enzymes (batroxobin and flavoxobin). Key amino-acid residues (His43, Asp88, Ser182 and Asp176) that are thought to be involved in the substrate cleavage and in the substrate-binding reaction are conserved. Ancrod contains 13 cysteine residues. Based on alignment with the amino-acid sequences of trypsin and batroxobin, six disulphide bridges can be predicted to be present in the ancrod protein. The existence of a free cysteine, which changes the common sequence surrounding the Ser182 active site from Gly-Asp-Ser-Gly-Gly-Pro to Cys-Asp-Ser-Gly-Gly-Pro, is unusual for a serine protease.
Au
L C
LC
Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, Republic of China.
Lin
S B
SB
Chou
J S
JS
Teh
G W
GW
Chang
K J
KJ
Shih
C M
CM
D000595:Amino Acid Sequence; D000721:Ancrod / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003435:Crotalid Venoms / Q000737:chemistry*; D004247:DNA / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D017421:Sequence Analysis; D017422:Sequence Analysis, DNA
C031442:Agkistrodon venoms; D003435:Crotalid Venoms; D004247:DNA; D000721:Ancrod