Biomaterial Database

Kinetic studies of the Serratia marcescens extracellular nuclease isoforms. 1994

M N Filimonova, and K L Krause, and M J Benedik

Department of Biochemical and Biophysical Sciences, University of Houston, TX 77204-5934.

Kinetic studies on the two major isoforms of Serratia marcescens nuclease, Sm2 and Sm1, have revealed them to be functionally equivalent. Both isoforms display marked substrate inhibition by DNA and RNA. They both require magnesium for optimal activity, but retain low catalytic activity in its absence. Both are moderately inhibited by mononucleotides including 5'-ATP, 5'-AMP, 5'-TTP and 3'5'-pTp. The two strongest mononucleotide inhibitors studied, 5'-ATP and 5'-AMP, display inhibition constants, KI, on the order of 10(-5) M. In assessing the strength of mononucleotide inhibition the type of nucleotide base appears to be more important than the number of phosphate moieties.

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.
D009711	Nucleotides	The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)	Nucleotide
D011756	Diphosphates	Inorganic salts of phosphoric acid that contain two phosphate groups.	Diphosphate,Pyrophosphate Analog,Pyrophosphates,Pyrophosphate Analogs,Analog, Pyrophosphate
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004706	Endodeoxyribonucleases	A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
D004722	Endoribonucleases	A family of enzymes that catalyze the endonucleolytic cleavage of RNA. It includes EC 3.1.26.-, EC 3.1.27.-, EC 3.1.30.-, and EC 3.1.31.-.	Endoribonuclease
D005246	Feedback	A mechanism of communication within a system in that the input signal generates an output response which returns to influence the continued activity or productivity of that system.	Feedbacks
D012331	RNA, Fungal	Ribonucleic acid in fungi having regulatory and catalytic roles as well as involvement in protein synthesis.	Fungal RNA
D012706	Serratia marcescens	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria found in soil, water, food, and clinical specimens. It is a prominent opportunistic pathogen for hospitalized patients.