Identification of alpha(1)-antitrypsin variants in plasma with the use of proteomic technology.
BACKGROUND
Proteomic technology permits the investigation of genetic metabolic diseases at the level of protein expression. Changes in the expression, polypeptide structure, and posttranslational modification of individual proteins can be detected in complex mixtures of proteins.


METHODS
We used high-resolution two-dimensional polyacrylamide gel electrophoresis to separate isoforms of plasma proteins and detect abnormalities of mass and/or charge. We confirmed the identity of the separated proteins by in-gel digestion with proteases and N-glycanases and then analyzed the released peptides and glycans by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry.


RESULTS
Complete characterization of the polypeptide sequences and glycosylation of alpha(1)-antitrypsin isoforms was achieved in plasma from controls and from patients with three different known alpha(1)-antitrypsin deficiencies and congenital disorder of glycosylation type Ia.


CONCLUSIONS
This study shows that proteomic techniques are a powerful and sensitive means of detecting changes in the amino acid sequence and abnormal posttranslational modifications of specific proteins in a complex biologic matrix.
Mills
K
K
Biochemistry Endocrinology and Metabolism Unit, Institute of Child Health at Great Ormond Street Hospital, University College London, 30 Guilford St., London WC1 N 1EH, United Kingdom.
Mills
P B
PB
Clayton
P T
PT
Johnson
A W
AW
Whitehouse
D B
DB
Winchester
B G
BG
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006801:Humans; D007525:Isoelectric Focusing; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D020543:Proteome; D000515:alpha 1-Antitrypsin / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
D020033:Protein Isoforms; D020543:Proteome; D000515:alpha 1-Antitrypsin