Amino acid sequence of rabbit carbonic anhydrase II.

The amino acid sequence of the high activity form of erythrocyte carbonic anhydrase, carbonic anhydrase II, purified from rabbit erythrocytes has been determined. This sequence was determined primarily from the cyanogen bromide and tryptic peptides through use of automated Edman degradation procedures. The ordering of the peptides from rabbit carbonic anhydrase II was based on the high degree of homology between the rabbit enzyme and the homologous enzymes derived from sheep, bovine, and human erythrocytes. The function of certain residues is discussed in the context of these three known sequences and the previously reported three-dimensional structure of human carbonic anhydrase II. Possible microheterogeneity of rabbit carbonic anhydrase II is also discussed.

Chemical characterization of a new Japanese variant of carbonic anhydrase I, CA INagasaki 1 (76 arg leads to gln).

A new inherited variant of carbonic anhydrase I (CA I), designated CA INagasaki 1 (CA INGS 1), was discovered during a survey of hemolysates from 5852 individuals from the cities of Hiroshima and Nagasaki in Japan. Analysis of the amino acid composition of a tryptic peptide from the CA INGS 1 variant indicated that a glutaminyl residue was substituted for an arginyl residue at position 76. Heat degradation studies showed that the CA INGS 1 variant was less stable than normal CA I. The CO2 hydrase and esterase activities of the normal and variant carbonic anhydrases I, as well as the relative amounts of the two enzymes in heterozygotes, were similar.

Amino acid substitution and chemical characterization of a Japanese variant of carbonic anhydrase I: CA I Hiroshima-1 (86 Asp replaced by Gly).

An electrophoretic variant of red cell carbonic anhydrase I, designated CA I Hiroshima-1, has been observed in 12 apparently unrelated individuals during a survey of 13,019 individuals from the cities of Hiroshima and Nagasaki, Japan. Analyses of tryptic and chymotryptic peptide patterns of this CA I variant purified from 8 of the 12 individuals revealed the same altered peptides in each case. Examination of the amino acid sequence of an altered tryptic peptide purified from one of the variants showed that the aspartic acid residue at position 86 was replaced by a glycine residue. Thermostability studies demonstrated that all samples of CA I Hiroshima-1 were less stable than normal CA I. The specific esterase (p-nitrophenyl acetate) activities of the normal and variant CA I isozymes were essentially the same. The difference spectra of the normal and variant enzymes were essentially the same. The isoelectric focusing patterns of CA I Hiroshima-1 showed a different pattern of minor bands to those produced by normal CA I. The relative amounts of the normal and variant enzymes purified from single heterozygous individuals were similar.