PMID- 6615816
OWN - NLM
STAT- MEDLINE
DCOM- 19831123
LR  - 20211008
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 22
IP  - 17
DP  - 1983 Aug 16
TI  - Kinetics of bovine milk lipoprotein lipase and the mechanism of enzyme activation 
      by apolipoprotein C-II.
PG  - 4041-7
AB  - The kinetics of bovine milk lipoprotein lipase (LPL) were studied in order to 
      determine the reaction mechanism of this enzyme. Reaction velocities were 
      determined at varying concentrations of emulsified trioleoylglycerol (TG) and 
      different fixed concentrations of apolipoprotein C-II (C-II) or at varying C-II 
      concentrations and different fixed concentrations of TG. Neither the apparent 
      Km(TG) nor the apparent Km(C-II) was affected by varying the concentrations of 
      C-II or TG, respectively. However, C-II increased the apparent Vmax for the 
      enzyme about 20-fold. The following kinetic parameters were calculated from 
      Lineweaver-Burk plots: Km(C-II) = 2.5 X 10(-8) M and Km (TG) = 2.5 X 10(-3) M. 
      The dissociation constant (KS) of the enzyme-TG binary complex was determined 
      from Scatchard plots to be 7.6 X 10(-8) M. Heparin was found to be a competitive 
      dead-end inhibitor against both TG and C-II. Tricapryloylglycerol represented a 
      competitive inhibitor against TG but a noncompetitive inhibitor against C-II. 
      C-II was shown to interact with dansylated bovine milk LPL, increasing its 
      fluorescent emission by inducing a conformational change in the enzyme. Based on 
      these studies, it was concluded that the LPL-catalyzed reaction follows a random, 
      bireactant, rapid-equilibrium mechanism and the role of C-II in the activation 
      process involves an increase in the catalytic rate constant (Kp) resulting from 
      conformational changes of LPL induced by C-II.
FAU - Posner, I
AU  - Posner I
FAU - Wang, C S
AU  - Wang CS
FAU - McConathy, W J
AU  - McConathy WJ
LA  - eng
GR  - HL-23181/HL/NHLBI NIH HHS/United States
GR  - HL-23705/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Apolipoprotein C-II)
RN  - 0 (Apolipoproteins)
RN  - 0 (Apolipoproteins C)
RN  - EC 3.1.1.34 (Lipoprotein Lipase)
SB  - IM
MH  - Animals
MH  - Apolipoprotein C-II
MH  - Apolipoproteins/*blood/pharmacology
MH  - *Apolipoproteins C
MH  - Cattle
MH  - Enzyme Activation
MH  - Humans
MH  - Kinetics
MH  - Lipoprotein Lipase/*metabolism
MH  - Mathematics
MH  - Milk/*enzymology
MH  - Protein Binding
EDAT- 1983/08/16 00:00
MHDA- 1983/08/16 00:01
CRDT- 1983/08/16 00:00
PHST- 1983/08/16 00:00 [pubmed]
PHST- 1983/08/16 00:01 [medline]
PHST- 1983/08/16 00:00 [entrez]
AID - 10.1021/bi00286a008 [doi]
PST - ppublish
SO  - Biochemistry. 1983 Aug 16;22(17):4041-7. doi: 10.1021/bi00286a008.