Biomaterial Database

Enzymes of heterotherms: LDH of hibernating and normothermic little brown bats, Myotis lucifugus. 1978

T W Moon

Department of Biology, University of Ottawa, Ontario, Canada.

1. Lactate dehydrogenase (LDH) was isolated from pectoral or flight muscle, liver and heart of hibernating and normothermic bats, Myotis lucifugus. 2. Activities at high substrate concentrations and the interactions between substrate and enzyme were studied to evaluate possible adaptations associated with the extended period of depressed metabolism of this bat. 3. Activity levels in all tissues decreased with hibernation, although the magnitude was dependent upon both temperature and substrate concentration. In general, the extent of decrease was in the order pectoral muscle greater than liver much greater than heart. 4. No correlation was found between the temperature sensitivity of the tissue LDHs as estimated by Ea-values, and the physiological state. 5. However, affinity parameters as estimated by Km-values were less temperature sensitive in hibernator tissues in contrast to the marked perturbations exhibited at temperature extremes in the normotherm enzymes. 6. It is suggested that changes in subunit quantities are in part responsible for these kinetic differences, and not major qualitative isozyme changes. 7. The net result of these effects is a reduced carbon flux to lactate during hibernation, but the maintenance of a potential for LDH catalyses during arousal.

UI	MeSH Term	Description	Entries
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007770	L-Lactate Dehydrogenase	A tetrameric enzyme that, along with the coenzyme NAD+, catalyzes the interconversion of LACTATE and PYRUVATE. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.	Lactate Dehydrogenase,Dehydrogenase, L-Lactate,Dehydrogenase, Lactate,L Lactate Dehydrogenase
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D011773	Pyruvates	Derivatives of PYRUVIC ACID, including its salts and esters.
D002685	Chiroptera	Order of mammals whose members are adapted for flight. It includes bats, flying foxes, and fruit bats.	Bats,Flying Foxes,Horseshoe Bats,Pteropodidae,Pteropus,Rhinolophus,Rousettus,Bat, Horseshoe,Bats, Horseshoe,Foxes, Flying,Horseshoe Bat
D006605	Hibernation	The dormant state in which some warm-blooded animal species pass the winter. It is characterized by narcosis and by sharp reduction in body temperature and metabolic activity and by a depression of vital signs.	Hibernation, Artificial,Induced Hibernation,Artificial Hibernation,Artificial Hibernations,Hibernation, Induced,Hibernations,Induced Hibernations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia