%0 Journal Article %J Proteins %D 1997 %T A method for the prediction of surface "U"-turns and transglobular connections in small proteins %A Andrzej Koliński %A Jeffrey Skolnick %A Adam Godzik %A Wei-Ping Hu %K Algorithms %K Amino Acid Sequence %K Animals %K Humans %K Molecular Sequence Data %K Protein Folding %K Protein Structure %K Proteins %K Proteins: chemistry %K Secondary %X A simple method for predicting the location of surface loops/turns that change the overall direction of the chain that is, "U" turns, and assigning the dominant secondary structure of the intervening transglobular blocks in small, single-domain globular proteins has been developed. Since the emphasis of the method is on the prediction of the major topological elements that comprise the global structure of the protein rather than on a detailed local secondary structure description, this approach is complementary to standard secondary structure prediction schemes. Consequently, it may be useful in the early stages of tertiary structure prediction when establishment of the structural class and possible folding topologies is of interest. Application to a set of small proteins of known structure indicates a high level of accuracy. The prediction of the approximate location of the surface turns/loops that are responsible for the change in overall chain direction is correct in more than 95% of the cases. The accuracy for the dominant secondary structure assignment for the linear blocks between such surface turns/loops is in the range of 82%. %B Proteins %V 27 %P 290–308 %8 feb %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/9061792 %0 Journal Article %J Protein Science: a Publication of the Protein Society %D 1995 %T Are proteins ideal mixtures of amino acids? Analysis of energy parameter sets %A Adam Godzik %A Andrzej Koliński %A Jeffrey Skolnick %K Amino Acid Sequence %K Amino Acids %K Crystallography %K Databases %K Factual %K Magnetic Resonance Spectroscopy %K Mathematics %K Models %K Protein Conformation %K Protein Folding %K Proteins %K Proteins: chemistry %K Theoretical %K Thermodynamics %K X-Ray %X Various existing derivations of the effective potentials of mean force for the two-body interactions between amino acid side chains in proteins are reviewed and compared to each other. The differences between different parameter sets can be traced to the reference state used to define the zero of energy. Depending on the reference state, the transfer free energy or other pseudo-one-body contributions can be present to various extents in two-body parameter sets. It is, however, possible to compare various derivations directly by concentrating on the "excess" energy-a term that describes the difference between a real protein and an ideal solution of amino acids. Furthermore, the number of protein structures available for analysis allows one to check the consistency of the derivation and the errors by comparing parameters derived from various subsets of the whole database. It is shown that pair interaction preferences are very consistent throughout the database. Independently derived parameter sets have correlation coefficients on the order of 0.8, with the mean difference between equivalent entries of 0.1 kT. Also, the low-quality (low resolution, little or no refinement) structures show similar regularities. There are, however, large differences between interaction parameters derived on the basis of crystallographic structures and structures obtained by the NMR refinement. The origin of the latter difference is not yet understood. %B Protein Science: a Publication of the Protein Society %V 4 %P 2107–2117 %8 oct %G eng %U http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2142984&tool=pmcentrez&rendertype=abstract %R 10.1002/pro.5560041016 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 1993 %T From independent modules to molten globules: observations on the nature of protein folding intermediates %A Jeffrey Skolnick %A Andrzej Koliński %A Adam Godzik %K Binding Sites %K Isomerases %K Isomerases: chemistry %K Protein Disulfide-Isomerases %K Protein Folding %K Protein Structure %K Proteins %K Proteins: chemistry %K Secondary %B Proceedings of the National Academy of Sciences of the United States of America %V 90 %P 2099–100 %G eng %U http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=46030&tool=pmcentrez&rendertype=abstract