|
|
Interactions of Zn2+ ions with proteins and nucleic acids
DVOŘÁKOVÁ, Kateřina
Interaction of Zn2+ ions with proteins and nucleic acids Zinc is an important metal in biological systems. It is a strong Lewis acid, forms a stable Zn2+ ion and can exist in several coordination geometries. Zinc is required for the activity of more than 300 enzymes. In proteins zinc can either participate directly in chemical catalysis or can be important for maintaining protein structure and stability. In this work a dataset of high quality (resolution better than 3 Ǻ) crystal structures deposited in the Protein Data Bank on internet have been examined to identify typical zinc binding sites and to establish their coordination geometries. Totally 135 zinc binding sites found in 74 structures have been analyzed. The most frequent coordinating atoms are sulphur in cystein, NE2 and ND1 nitrogens in histidine followed by oxygen atoms in carboxylates of aspartic and glutamic acids. 67% of zinc binding sites were found to be four-coordinated with tetrahedral coordination geometry. In contrast Mg2+ cations show a clear preference to bind to oxygen atoms and to form octahedral cavities. We have not found any structure with a direct zinc coordination to DNA except the 1ZQT structure which was however excluded due to its low resolution (> 3 {\AA}). Similarly only three zinc binding sites have been found in RNA structures which were however determined in the protein free environment. All other zinc binding sites have been located in proteins even in the presence of the nucleic acids.
|
|
|
Fyzikálně-chemická charakterizace peptidů a bílkovin kapilárními elektromigračními metodami
Kašička, Václav ; Koval, Dušan ; Šolínová, Veronika ; Sázelová, Petra ; Prusík, Zdeněk
High-performance capillary electromigration methods, zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis and electrokinetic chromatography, are presented as powerful tools for physicochemical characterization of peptides and proteins.
|
|
| |
|
| |
|
| |
|
| |
|
| |
|
| |
|
| |
|
|
Interaction of sperm surface proteins in the reproduction process
Jonáková, Věra ; Kraus, Marek ; Maňásková, Pavla ; Liberda, J. ; Tichá, M.
Mammalian fertilization includes highly regulated biochemical interactions between complementary molecules located on the surfaces of both gametes as well as those present in the natural environment of the gametes. Boar seminal plasma proteins AQN, AWN spermadhesins and DQH protein that are bound to the sperm at ejaculation play important role in the reproduction process. Binding of sperm to epithelial cells, recognition of gametes and binding of sperm to glycoprotein of zona pellucida are mediated by protein-saccharide interaction, lektin-type interaction. Another type of interaction (protein-protein) participates in the formation of aggregated forms, which seem to be the natural functional forms of seminal plasma proteins. Protein aggregates form the sperm coating layers and their re-modeling in the female reproductive tract is imporatnt for the sperm capacitation and for the primary binding of spermto the ovum.
|
guest ::
