Purification and Characterization of Multiple Forms of Mutarotase from Hog Kidney Cortex
1982 Volume 91 Issue 6 Pages 1889-1898
Details
1982 Volume 91 Issue 6 Pages 1889-1898
The enzyme mutarotase [aldose 1-epimerase, EC 5. 1. 3. 3] from hog kidney cortex was separated into four fractions (designated types I, II, III, and IV in order of elution) by column chromatography on DEAF-cellulose. Two major forms, types I and II, were purified to homogeneity as judged by polyacrylamide gel electrophoresis and isoelectric focusing on thin layer polyacrylamide gel.
Types I, II, III, and IV had isoelectric points of 5.78, 5.48, 5.23, and 5.10, respectively. The following physicochemical properties were common to all four types: molecular weight, 41, 000; Km for α-D-glucose at pH 7.4 and 25°C, 19mM; optimum pH, 6.5-7.5; optimum temperature, 30-37°C; heat stability, up to 50°C.
On double immunodiffusion, the four types of mutarotase gave single precipitin lines, which fused completely with each other, against the antibody to purified type II enzyme.
Types I and II had an identical amino-terminal residue, arginine, and an identical carboxyl-terminal sequence, -(Phe-Phe-Ser-Val)-Val-Ala. The amino acid composition of type I was almost identical with that of type II. Very similar tryptic peptide maps were obtained from types I and II, with only a few points of variance.
These results suggest that the four types of hog kidney mutarotase are quite similar but not identical.
