Complete amino acid sequence of human liver cytosolic alanine aminotransferase (GPT) determined by a combination of conventional and mass spectral methods.

Abstract:

:The complete amino acid sequence of human liver cytosolic alanine aminotransferase (GPT) (EC 2.6.1.2) is presented. Two primary sets of overlapping fragments were obtained by cleavage of the pyridylethylated protein at methionyl and lysyl bonds with cyanogen bromide and Achromobacter protease I, respectively. Isolated peptides were analyzed with a protein sequencer or with a plasma desorption time of flight mass spectrometer and placed in the sequence on the basis of their molecular mass and homology to the sequence of rat GPT. The protein was found to be acetylated at the amino terminus and contained 495 amino acid residues. The Mr of the subunit was calculated to be 54,479, which was in good agreement with a Mr of 55,000 estimated by SDS-PAGE, and also indicated that the active enzyme with a Mr of 114,000 was a homodimer composed of two identical subunits. The amino acid sequence is highly homologous to that of rat GPT (87.9% identity) recently determined [Ishiguro, M., Suzuki, M., Takio, K., Matsuzawa, T., & Titani, K. (1991) Biochemistry 30, 6048-6053]. All of the crucial amino acid residues are conserved in human GPT, which seem to be hydrogen bonding to pyridoxal 5'-phosphate in rat GPT by the sequence homology to other alpha-aminotransferases with known tertiary structures.

journal_name

Biochemistry

journal_title

Biochemistry

authors

Ishiguro M,Takio K,Suzuki M,Oyama R,Matsuzawa T,Titani K

doi

10.1021/bi00107a013

subject

Has Abstract

pub_date

1991-10-29 00:00:00

pages

10451-7

issue

43

eissn

0006-2960

issn

1520-4995

journal_volume

30

pub_type

杂志文章