Homology models of human gamma-crystallins: structural study of the extensive charge network in gamma-crystallins. 2003

Asmat Salim, and Zafar H Zaidi
H.E.J. Research Institute of Chemistry, International Center for Chemical Sciences, University of Karachi, Karachi 75270, Pakistan. prochem@hotmail.com

The lens is composed of highly stable and long-lived proteins, the crystallins which are divided into alpha-, beta-, and gamma-crystallins. Human gamma-crystallins belong to the betagamma superfamily. A large number of gamma-crystallins have been sequenced and have been found to share remarkable sequence homology with each other. Some of the gamma-crystallins from various sources have also been elucidated structurally by X-ray crystallographic or NMR spectroscopic experiments. Their three-dimensional structures are also similar having consisted of two domains each possessing two Greek key motifs. In this study we have constructed the comparative or homology models of the four major human gamma-crystallins, gammaA-,gammaB-, gammaC-, and gammaD-crystallins and studied the charge network in these crystallins. Despite an overall structural similarity between these crystallins, differences in the ion pair formation do exist which is partly due to the differences in their primary sequence and partly due to the structural orientation of the neighboring amino acids. In this study, we present an elaborate analysis of these charged interactions and their formation or loss with respect to the structural changes.

UI MeSH Term Description Entries
D007477 Ions An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
D008958 Models, Molecular Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures. Molecular Models,Model, Molecular,Molecular Model
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D017386 Sequence Homology, Amino Acid The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species. Homologous Sequences, Amino Acid,Amino Acid Sequence Homology,Homologs, Amino Acid Sequence,Homologs, Protein Sequence,Homology, Protein Sequence,Protein Sequence Homologs,Protein Sequence Homology,Sequence Homology, Protein,Homolog, Protein Sequence,Homologies, Protein Sequence,Protein Sequence Homolog,Protein Sequence Homologies,Sequence Homolog, Protein,Sequence Homologies, Protein,Sequence Homologs, Protein
D017433 Protein Structure, Secondary The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to ALPHA-HELICES; BETA-STRANDS (which align to form BETA-SHEETS), or other types of coils. This is the first folding level of protein conformation. Secondary Protein Structure,Protein Structures, Secondary,Secondary Protein Structures,Structure, Secondary Protein,Structures, Secondary Protein
D017434 Protein Structure, Tertiary The level of protein structure in which combinations of secondary protein structures (ALPHA HELICES; BETA SHEETS; loop regions, and AMINO ACID MOTIFS) pack together to form folded shapes. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Tertiary Protein Structure,Protein Structures, Tertiary,Tertiary Protein Structures
D055672 Static Electricity The accumulation of an electric charge on a object Electrostatic,Electrostatics,Static Charge,Charge, Static,Charges, Static,Electricity, Static,Static Charges
D020539 Sequence Analysis, Protein A process that includes the determination of AMINO ACID SEQUENCE of a protein (or peptide, oligopeptide or peptide fragment) and the information analysis of the sequence. Amino Acid Sequence Analysis,Peptide Sequence Analysis,Protein Sequence Analysis,Sequence Determination, Protein,Amino Acid Sequence Analyses,Amino Acid Sequence Determination,Amino Acid Sequence Determinations,Amino Acid Sequencing,Peptide Sequence Determination,Protein Sequencing,Sequence Analyses, Amino Acid,Sequence Analysis, Amino Acid,Sequence Analysis, Peptide,Sequence Determination, Amino Acid,Sequence Determinations, Amino Acid,Acid Sequencing, Amino,Analyses, Peptide Sequence,Analyses, Protein Sequence,Analysis, Peptide Sequence,Analysis, Protein Sequence,Peptide Sequence Analyses,Peptide Sequence Determinations,Protein Sequence Analyses,Protein Sequence Determination,Protein Sequence Determinations,Sequence Analyses, Peptide,Sequence Analyses, Protein,Sequence Determination, Peptide,Sequence Determinations, Peptide,Sequence Determinations, Protein,Sequencing, Amino Acid,Sequencing, Protein
D020816 Amino Acid Motifs Three-dimensional protein structural elements that are composed of a combination of secondary structures. They include HELIX-LOOP-HELIX MOTIFS and ZINC FINGERS. Motifs are typically the most conserved regions of PROTEIN DOMAINS and are critical for domain function. However, the same motif may occur in proteins or enzymes with different functions. AA Motifs,Motifs, Amino Acid,Protein Motifs,Protein Structure, Supersecondary,Supersecondary Protein Structure,AA Motif,Amino Acid Motif,Motif, AA,Motif, Amino Acid,Motif, Protein,Motifs, AA,Motifs, Protein,Protein Motif,Protein Structures, Supersecondary,Supersecondary Protein Structures

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