scholarly journals The titration curve of insulin in the presence of various bivalent metal ions

1968 ◽  
Vol 106 (4) ◽  
pp. 777-781 ◽  
Author(s):  
John Graae
Keyword(s):  
Metal Ions ◽  
Titration Curve ◽  
Amino Groups ◽  
Dilute Solutions ◽  
Bivalent Metal ◽  
Titration Curves ◽  
Bivalent Metal Ions ◽  
Presence And Absence ◽  
The Difference

1. Titration curves of insulin in the presence and absence of various metal ions are reported. 2. The difference in base consumption with and without the metal ions is compared with calculated curves. 3. These experiments suggest that in dilute solutions Zn2+ and Cu2+ ions are bound to α-amino groups.

scholarly journals Separation and properties of two arylamidases from rat cardiac-muscle extracts

1977 ◽  
Vol 163 (3) ◽  
pp. 565-570 ◽  
Author(s):  
A F Bury ◽  
T Coolbear ◽  
C R Savery
Keyword(s):  
Metal Ions ◽  
Cardiac Muscle ◽  
Rat Heart ◽  
Bivalent Metal ◽  
Ph Optimum ◽  
Minor Peak ◽  
Bivalent Metal Ions ◽  
Stimulation Of

Two main arylamidase activities were separated from a particle-free supernatant of rat heart by chromatography on DEAE-Sephadex. Although both enzymes hydrolysed L-leucine 4-nitroanilide, only peak-II enzyme hydrolysed L-lysine 4-nitroanilide. A third minor peak (Ia) contained an enzyme that was active mainly on the L-lysine 4-nitroanilide. The mol.wts. of the enzymes in peaks I and II were approx. 257000 and 105000 respectively. The pH optimum was approx. pH7.0 for peak-I enzyme and 7.0-8.0 for peak-II enzyme. Both enzymes were inhibited by addition of puromycin, p-hydroxymercuribenzoate, o-phenanthroline and bivalent metal ions. Addition of dithiothreitol resulted in stimulation of both activities. Dialysis against o-phenanthroline resulted in inhibition of peak-I and -II enzymes, but after dialysis against EDTA only peak-II enzyme was inhibited.

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