Biomaterial Database

Effect of pH on interactions between DNA and high-mobility group protein HMG1. 1994

L A Kohlstaedt, and R D Cole

Department of Molecular and Cell Biology, University of California, Berkeley 94720.

Fluorescence quenching was used to test the effect of pH changes on the binding of high-mobility group protein 1 (HMG1) to double-stranded and single-stranded DNA. At pH 7.5, the binding constant K for double-stranded DNA was 3 x 10(6) M-1, the binding site size n was 13, and the cooperativity factor q was 78, while at pH 6 the corresponding values were K = 12 x 10(6) M-1, n = 54, and q = 770. For the binding of HMG1 to single-stranded DNA at pH 7.5, the values were K = 2 x 10(6) M-1, n = 7, and q = 60, whereas at pH 6 they were K = 3 x 10(6) M-1, n = 14, and q = 440. Denaturation of HMG1 by oxidation of its sulfhydryl groups substantially affected the binding parameters. At pH 6, double-stranded DNA bound oxidized HMG1 with K = 6 x 10(6) M-1, n = 16, and q = 200, and single-stranded DNA bound with K = 3 x 10(6) M-1, n = 7, and q = 180. The sensitivity of the double-stranded DNA-HMG1 interaction to pH, along with an earlier report of a sharp optimum of binding at 140 mM NaCl, reveals a potential for in vivo regulation of the strength and mode of HMG1 binding by DNA through the action of analogous factors in the cellular milieu.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011489	Protein Denaturation	Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.	Denaturation, Protein,Denaturations, Protein,Protein Denaturations
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
D004277	DNA, Single-Stranded	A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.	Single-Stranded DNA,DNA, Single Stranded,Single Stranded DNA
D006609	High Mobility Group Proteins	A family of low-molecular weight, non-histone proteins found in chromatin.	HMG Proteins,Calf Thymus Chromatin Protein HMG,High Mobility Group Chromosomal Proteins
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence