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W L Mattice

Publications and source records attributed to W L Mattice.

13 recordsLinked to original sources
PubMed1990

Range of the influence of the carbohydrate moiety on the conformation of the poly(amino acid) backbone in glycosylated mucins.

The influence of glycosylation on the conformational properties of porcine submaxillary gland mucin has been investigated using rotational isomeric state theory. The specific objective was to determine the conditions under which the polypeptide has the relatively large mean square unperturbed radius of gyration mean value of s2(0), demanded by the measurements of Shogren et al., while retaining the overall architecture of a random coil. The mean square dimensions were monitored as the dimensionless characteristic ratio defined as C = mean value of s2(0)/npl2p, and the overall architecture was monitored by another dimensionless ratio mean value of r2(0)/mean value of s2(0), where mean value of r2(0) denotes the mean square unperturbed end-to-end distance. The computed values of C cannot reproduce the measured values if the conformational influence of glycosylation is restricted to each Ser or Thr, or if this influence extends only as far as their nearest neighbors. Values of C compatible with experiment can be obtained if the influence extends to next nearest neighbors. The behavior of the computed values of mean value of r2(0)/mean value of s2(0) permits an assignment of 7 +/- 1 as the likely upper limit to the number of consecutive amino acid residues that experience alterations in phi and psi if the sequence contains a glycosylated Ser or Thr.

Amino Acid Sequence↗
PubMed1976

Conformational properties of the complexes formed by proteins and sodium dodecyl sulfate.

Circular dichroism spectra have been obtained for albumin, alpha-chymotrypsinogen, collagen, concanavalin A, elastase, hemoglobin, histone f2b, alpha-lactalbumin, lactate dehydrogenase, beta-lactoglobulin, lysozyme, myoglobin, papain, ribonuclease A, and thermolysin in the presence of sodium dodecyl sulfate and dithiothreitol. While all spectra have the shape anticipated for a mixture of random coil and alpha helix, the intensities differ markedly ([theta]222 ranges from --1400 to --15 000 deg cm2/dmol). The variation in the circular dichroism can be quantitatively explained by a model which assumes that the arginyl, histidyl, and lysyl residues have an enhanced probability of propagating a helical segment in the presence of the detergent. The model also permits the computation of dimensional properties (unperturbed end-to-end distance and radius of gyration) for polypeptides of known amino acid sequence. Such computations have been performed for 67 proteins. The computed dimensions are compatible with experimental values and with the molecular weight dependence of the transport properties of the complexes. Furthermore, the model can account for the abnormal transport properties of the sodium dodecyl sulfate complexes formed by ribonuclease A, collagen fragments, and histones f2a1, f2a2, f2b, and f3. Even though some of the protein--sodium dodecyl sulfate complexes have helical contents as high as 50%, their overall conformation more closely approximates that of a random coil than a rod.

Amino Acids↗
PubMedDate not supplied

Hydrodynamic properties and unperturbed dimensions of poly(gamma-hydroxy-L-proline) in aqueous solution.

Intrinsic viscosities and sedimentation coefficients have been measured as a function of molecular weight for poly(gamma-hydroxy-L-proline) in water. The molecular weight range covered is 9,000-35,000. High molecular weight poly(gamma-hydroxy-L-proline) in water has the hydrodynamic behavior of a random coil immersed in a good solvent, as judged by d ln [eta]/d ln M, d ln so/d ln M, dbeta/dM, and the size of beta[= nu rho (-1)]/1/3etaM-2/3(1 - nurho)-1]. The characteristic ratio, ((r2)o/nplp2) infinity, is found to be 15.9 +/- 1.6, which is not significantly different from the result of 13.7 +/- 0.9 obtained for poly(L-proline) by Mattice and Mandelkern under the same conditions. This observation casts doubt on the importance of intrachain hydrogen bonded bridges from the hydroxyl group to a carbonyl oxygen via a water molecule. The characteristic ratios and the effects of calcium chloride on the hydroynamic properties suggest that poly(L-proline) and poly(gamma-hydroxy-L-proline) possess a similar source of flexibility which is often overlooked. Two possibilities for this flexibility are a second energy minimum about the Calpha-C' bond and cis-trans isomerization about the peptide bond.

Hydrogen Bonding↗
PubMedDate not supplied

Unperturbed dimensions for homopolypeptides and sequential copolypeptides cross-linked via a disulfide bond.

Rotational isomeric state theory, in the form appropriate for branched molecules, has been used to calculate the mean-square unperturbed radius of gyration, (s2)0, for cross-linked polyglycine, poly(L-alanine), poly(L-proline), poly(L-alanyl-D-alanine), poly(L-propyl-L-prolylglycine), poly(L-prolyl-L-alanylglycine, poly(glycyl-L-alanyl-L-proline), and poly(L-alanyl-L-alanylglycine). The central amino acid residue in each polypeptide chain is replaced by the L-cysteinyl residue involved in cross-link formation. Each cross-linked molecular is considered to contain two trifunctional branch points, the alpha-carbon atoms of the two L-cysteinyl residues. Random flight statistics provide a poor estimate for g, defined as the ratio of (s2)0 for branched and linear polypeptides containing the same number of amino acid residues, for molecules of moderate molecular weight. The values of g obtained by random flight statistics and rotational isomeric state theory merge as the molecular weight becomes infinite. Deviations of g from its random flight value correlate with the size of the characteristic ratio, (s2)0/nplp2, for the linear polypeptides. The number of peptide bonds is np, and lp denotes the distance between neighboring alpha carbon atoms. Random flight statistics perform better in estimating the change in (s2)0 accompanying the cross-linking of the two polypeptide chains than it does in the estimation of g.

Amino Acid Sequence↗
PubMedDate not supplied

Unperturbed dimensions of disordered proteins containing an interchain disulfide cross-link.

Mean-square unperturbed radii of gyration, (s2)0, have been calculated for several proteins cross-linked via an interchain disulfide bond. Thirty different polypeptide chains were used. Characteristic ratios tend to be smaller for cross-linked proteins than for the uncross-linked chains, although exceptions to this generalization do exist. Random flight statistics tend to overestimate the value of g, defined as the ratio of (s2)0 for the cross-linked protein to (s2)0 for analogous linear polypeptide chain containing the same number of amino acid residues. The parameter fi, defined as the ratio of the (s2)0 for the ith uncross-linked polypeptide chain and the cross-linked protein, is usually more accurately estimated by random flight statistics than is g. When the cross-link connects two chains of identical amino acid sequence, the values of fi obtained via random flight statistics are within 6% of those provided by rotational isomeric state theory.

Amino Acid Sequence↗