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A new proalbumin variant: Albumin Jaffna (−1 Arg→Leu)
Author(s) -
Galliano Monica,
Minchiotti Lorenzo,
Stoppini Monica,
Tàrnoky Andràs L.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81109-3
Subject(s) - chromatofocusing , chemistry , albumin , isoelectric point , sephadex , trypsin , chromatography , serum albumin , biochemistry , column chromatography , enzyme
Albumin Jaffna is an electrophoretically slowly moving genetic variant of human serum albumin found in two members of a Tamil family from Jaffna (Northern Sri Lanka), both heterozygous for the abnormal protein. Sequential analysis of albumin Jaffna, purified from serum by ion exchange chromatography on DEAE Sephadex and Mono Q columns, revealed that this variant is a new abnormal proalbumin, arising from a −1 Arg→Leu substitution, which prevents the proteolytic removal of the N‐terminal hexapeptide and allows the mutated proalbumin to enter the circulation. The presence of two additional positive charges is in keeping with the decreased electrophoretic mobility of albumin Jaffna, as well as with its isoelectric point of 5.01, determined by chromatofocusing on a Mono P column. The variant is selectively cleaved by trypsin in vitro, leaving leucine −1 as N‐terminal residue.