Abstract
1. 1. Malate dehydrogenase (EC 1.1.1.37) was 100-fold purified from porcine erythrocytes, and a partially purified preparation, with specific activity of 3000–4200 U/mg, was obtained. Chromatographic and kinetic characteristics, and inhibition patterns, indicate that porcine erythrocytes possess a single isoenzyme of malate dehydrogenase with cytoplasmic, rather than mitochondrial characteristics. 2. 2. Partially purified erythrocyte malate dehydrogenase has the following limiting Michaelis constants for substrates: 56 gmM for NADH and 62 gmM for oxaloacetate at pH 7.6, and 135 gmM for NAD + and 1200 gmM for l-malate at pH 9.0, respectively. 3. 3. Molecular weight of the erythrocyte isoenzyme (70,000), estimated by the gel filtration method, is identical with the molecular weights of mitochondrial and supernatant malate dehydrogenase isoenzymes from pig heart. 4. 4. No meaningful metabolic pathway has been found which would connect the malate dehydrogenase reaction with the other metabolic functions of the erythrocyte. Therefore, the proposition has been advanced that the large quantity of malate dehydrogenase-activity (1-1.2 million U/l of whole blood) in erythrocytes, represents a functionless remainder after the dedifferentiation of reticulocytes into the mature red blood cells.
Sign-in/Register to access full text options 
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.
