A New Mutation Destroying Disulphide Bridging in the C-Terminal Domain of Lipoprotein Lipase

• Published in: Biochemical and biophysical research communications 1996-10, Vol.227 (1), p.189-194
• Main Authors: Henderson, Howard E., Hassan, Fahri, Marais, David, Hayden, Michael R.
• Format: Article
• Language: English
• Subjects: Adult; Animals; Catalysis; COS Cells; Disulfides - chemistry; Humans; Hypertriglyceridemia - genetics; Lipid Metabolism, Inborn Errors - genetics; Lipoprotein Lipase - chemistry; Lipoprotein Lipase - genetics; Lipoprotein Lipase - metabolism; Male; Mutation; Pedigree; Protein Folding
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1996.1487

Lipoprotein lipase (LPL) is one of two intravascular lipases involved in the lipolysis of the triglyceride core of circulating lipoproteins. The occurrence of patients with genetic deficiencies has provided insight into the structure and function relationships of this lipase. It is now known that LPL manifests a two domain structure with the N-terminal domain of greater structural and functional significance as it contains the active site and interfacial binding motifs. We report on a Cys418Tyr substitution in the C-terminal domain which disrupts the only disulphide bridge in the region and is associated with catalytic deficiency in post-heparin plasma. This result was unexpected as previousin vitroassessment of the functional significance of disulphide bridging had shown that while the 3, N-terminal disulphides were critical for enzyme function, loss of the only C-terminal disulphide minimally affected catalytic activity. We generated the Cys418Tyr mutant by site-directed mutagenesis and show that it manifests 48% of normal activityin vitro,while the companion variants, Cys438Ser and Cys418Ser-Cys438Ser, are less affected with activities at 76% and 78% of normal.