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M Bálint

Publications and source records attributed to M Bálint.

16 recordsLinked to original sources
PubMed1995

Trypsin complexed with alpha 1-proteinase inhibitor has an increased structural flexibility.

Mutant rat trypsin Asp189Ser was prepared and complexed with highly purified human alpha 1-proteinase inhibitor. The complex formed was purified to homogeneity and studied by N-terminal amino acid sequence analysis and limited proteolysis with bovine trypsin. As compared to uncomplexed mutant trypsin, the mutant enzyme complexed with alpha 1-proteinase inhibitor showed a highly increased susceptibility to enzymatic digestion. The peptide bond selectively attacked by bovine trypsin was identified as the Arg117-Val118 one of trypsin. The structural and mechanistic relevance of this observation to serine proteinase-substrate and serine proteinase-serpin reactions are discussed.

Amino Acid Sequence↗
PubMed1985

Localization of a new proteolytic site accessible in oxidized myosin rod.

We have compared the proteolysis pattern of reduced and oxidized myosin rods in which the five pairs of SH-groups were interchain crosslinked by employing CuCl2 or 5,5'-dithiobis-2-nitrobenzoate. In the tryptic digest of oxidized rod three new fragments appeared on SDS-polyacrylamide gel electrophoresis (chain masses of 100, 45, and 25 kDa). Based on the N-terminal sequences of the isolated peptides, it is concluded that oxidation creates a new cleavage site 102 residues away from the N-terminus of the rod, in the vicinity of one of the modified SH-groups (Cys-108). This observation indicates that S-S crosslinking of myosin rod leads to a local unfolding of the coiled-coil structure.

Amino Acid Sequence↗
PubMed1985

Paracrystalline assemblies of light meromyosins with various chain weights.

Paracrystals formed from well defined insoluble fragments of myosin rod: LMM-A, LMM-B, LMM-C, and LMM-D with apparent chain weights of 78 000, 72 000, 68 000, and 56 000, respectively (Nyitray et al., 1983) were studied in the electron microscope with a negative staining technique. All fragments formed tactoids with 14.3 and 43 nm periodicities as well as aperiodic tactoids and sheets. Tactoids and sheets described earlier with a 43 nm periodicity and a pattern of alternating light bands 10 nm wide and dark bands 33 nm wide were observed in LMM-A preparations only. LMM-B and LMM-C formed tactoids with a 43 nm periodicity but without the diversified band pattern. LMM-D formed sheets and tactoids with a newly observed band pattern of alternating light bands 23 nm wide and dark bands 20 nm wide. This pattern can be explained assuming the length of LMM-D molecules to be 66 nm which is fairly consistent with the chain weight of this fragment. A model for molecular arrangement in this type of paracrystal is presented. The model involves both parallel and antiparallel interactions with a parallel axial displacement of the molecules by 43 nm as suggested by Bennett (1981) for paracrystals formed from LMM molecules 90 nm long. It is deduced from the model that LMM-D is shorter than LMM-A by 15 nm at the NH2-terminal end and by 9 nm at the COOH-terminal end. LMM-D, like the other insoluble fragments of myosin rod, is also able to form square and hexagonal nets with an approximately 40 nm distance between lattice points. The structural features of the nets obtained from LMM-D can be explained assuming the same kinds of molecular interactions within the strands of the net as those in the sheets and tactoids with a 43 nm axial repeat. It is concluded that all insoluble fragments of myosin rod are able to form paracrystalline assemblies involving the same types of parallel and antiparallel interactions.

Animals↗
PubMed1984

Use of cationic detergents for polyacrylamide gel electrophoresis in multiphasic buffer systems.

An improved system for polyacrylamide gel electrophoresis in the presence of cationic detergents, cetyltrimethylammonium bromide and cetylpyridinium chloride, respectively, is described. An acidic discontinuous buffer system generated according to the theory of multiphasic zone electrophoresis developed by T. M. Jovin (1973, Biochemistry 12, 871-904) was used. It was optimized with respect to the operational conditions and to the desirable range of relative mobility values for the proteins that have molecular weights from 16,500 to 90,300. Also presented is a procedure for the elimination of interference from cationic detergents frequently encountered during staining of gels. The electrophoretic system was suitable for fractionating a wide variety of proteins. The technique can also be used to provide an alternative estimate of molecular weight. To fully account for accurate estimations, the Ferguson relationship between mobility and gel concentration and the relation of molecular weight to mobility at a single gel concentration were both considered. Examples reported in this paper include the separation and/or molecular weight determination of several common proteins, histones, and microfibrillar and myofibrillar proteins. The results suggest that electrophoresis in the presence of cationic detergents offers the same degree of reliability in analysis of most proteins as is provided by the anionic detergent sodium dodecyl sulfate electrophoresis.

Buffers↗
PubMed1981

The mechanism of limited tryptic proteolysis of heavy meromyosin as revealed by peptide analysis.

To elucidate some ambiguous details in the tryptic fragmentation scheme of HMM as given by Bálint et al. (J. Biol. Chem. 250 (1975) 6168; Arch. Biochem. Biophys. 190 (1978)793), the peptide fragments were isolated by a milligram scale preparative gel electrophoresis procedure. The dansyl-peptide map of the 20 kDal tryptic fragment obtained from tryptic heavy meromyosin (HMM) and that of a similar fragment from papainic subfragment-1 (S-1) were found to be nearly identical. This finding gives unequivocal proof of the location of the 17 kDal peptide stretch lost during digestion in the form of small peptides, at the C terminal part of the heavy chain backbone of HMM. The N terminals of the 150, 74, and 25 kDal fragments of the heavy chain isolated from HMM digested by trypsin under widely differing conditions were shown to be acetylated. The N terminal amino group of the other peptide fragments of HMM remains the same under widely differing conditions of digestion. We conclude that all the fragments are well defined polypeptides and digestion progresses by splitting from the C terminals formed by the primary splits.

Acetylation↗
PubMed1975

The substructure of heavy meromyosin. The effect of Ca2+ and Mg2+ on the tryptic fragmentation of heavy meromyosin.

Heavy meromyosin, obtained by tryptic digestion of myosin, containing two main polypeptides whose masses were estimated as 81,000 and 74,000 dlatons from Na dodecyl-SO4 polyacrylamide gel electrophoresis, was further digested with trypsin. The Ca2+-activated ATPase activity remainded unchanged and the K+-EDTA activity increased while various smaller fragments were formed. The formation of some of these fragments is affected by Ca2+ or Mg2+ as first shown by Bálint et al. (Bálint, M., Schaefer, A., Biro, N. A., Menczel, L., AND Fejes, E. (1971) J. Physiol. Chem. Phys. 3, 455). On the basis of the time course of the appearance of fragments the following relationship emerges: see article. The 64K leads to 60K step is inhibited by divalent cations, while the breakdown of the 74K fragment is accelerated. The effect of Ca2+ was maximal at 0 similar to 0.1 muM, that of Mg2+ at 10 muM. The original light chains of myosin are not present in the heavy meromyosin serving as the starting material, but peptide material appears on electrophoresis in positions starting material, but peptide material appears on electrophoresis in positions where the light chains would be found. The fragments marked by an asterisk are considered to ba alpha-helical on the basis of their solubility at low ionic strength after precipitation with ethanol (Bálint et al.). The fact that alpha helical fragments are derived from the 60,000-dalton fragment indicateds that it is adjacent to the light meromyosin in the intact myosin while the 74,000- dalton fragment would be part of heavy meromysoin subfragment 1. Chromatography of Sephadex G-200 separates fractions with ATPase activity corresponding to heavy meromyosin and heavy meromyosin subfragment 1. Electrophoresis of these Sephadex fractions suggests that the main peptide constituting heavy meromysoin subfragment 1 is connected by noncobalent forces to a portion of the rod that is not immediately adjacent to it in the primary sequence. The significance of this finding is discussed in terms of the flexibility of the myosin head.

Adenosine Triphosphatases↗