Abstract
We have determined the size of the functional unit of bovine lipoprotein lipase by radiation inactivation. This was done in five different situations: 1) in a buffer with high salt concentration. In this situation the enzyme is relatively soluble and stable. 2) For an enzyme-heparin complex. This may reflect the physiological state of the enzyme at the vascular endothelium, where it is believed to be bound to a heparin-like molecule. 3) In the presence of lipid substrate and 4) with lipid substrate and activator protein. Here most of the enzyme is adsorbed to the substrate droplets. 5) For an enzyme-detergent complex; another model for enzyme-lipid interaction. In all five situations the enzyme activity decayed as an exponential function of radiation dose, and the target sizes were similar. The target size did not vary with the concentration of lipase protein. The combined data for bovine lipoprotein lipase yield a functional size of 72 kDa which is close to that expected for a dimer, 77 kDa.
Highlights
Thiswas done in five different situations:1)in a buffer have previously studied some other physical properties of the with high salt concentration
Lipoprotein lipase was prepared from bovine milk by chromatography on heparin-Sepharose as described [11].The concentration of lipase protein in stock solutions was calculated from the absorbancy
After 1min, the samples were chilled on ice, aliquoted into glass adipose tissues gave values of 127 f 15 kDa [6].If these data were applicable to bovine lipoprotein lipase they would indicate that thefunctional unit is a trimer or tetramer, since the protein moiety of the subunit is 38.4 kDa [3]
Summary
Lipoprotein lipase was prepared from bovine milk by chromatography on heparin-Sepharose as described [11].The concentration of lipase protein in stock solutions was calculated from the absorbancy. Medical Research Council (13x3-727).The costs of publication of this effects of inactive lipase protein we carried out one experiment with article were defrayed in part by the payment of page charges. This an enzyme preparation which had lost more than 90% of its activity article must be hereby marked “aduertisernent” in accord- during storage at -20 “C. ance with 18U.S.C. Section 1734 solelyto indicate this fact. Using the slope of this inactivation curve, the target molecular weight was determined from M,= 6.4 X 10" St x k, where Stis a temperature factor which is 2.8 for an irradiation temperature of -135 "C [16]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
