Structure and dynamics of ordered hydrates and fibrous proteins by solid-state NMR

This thesis is divided into four chapters describing studies of structural waters in tri-peptides, one-dimensional water channels and two fibrous proteins elastin and collagen. The dissertation begins with the study of peptide hydrates Gly-Gly-Val·2H2O (GGV) and Gly-Ala-Leu·3H2O (GAL) where water molecules connect tripeptide units through hydrogen bonds, allowing alpha-helix propagation. Results indicate, that triply coordinated structural waters flip about a two-fold axis, while tetrahedral hydrates are only observed at low temperature (-65°C) due to intermediate (10 -3--10-5 s-1) dynamics.; In chapter two of the thesis, imidazole stabilized one-dimensional water channels are studied. Compounds reported here contain chains of water in different arrangements. All structural hydrates are hydrogen-bonded to either other waters or neutral amine groups. 2H NMR shows small amplitude librational dynamics for all compounds studied, which is a somewhat unexpected result.; The dynamics and structure of water are also important in elastin, a key protein in soft tissue function and pathology. Chapter three examines hydrate and polypeptide ordering in both elastic (hydrated) and brittle (dry) elastin fibers using solid-state NMR methods. The results demonstrate (i) that tightly bound waters are absent in both dry and hydrated elastin and (ii) that the backbone in the hydrated protein is predominantly highly disordered with large amplitude motions. This result indicates that structural models for elastin with well-defined 2° structure, such as a Type-II beta-turn repeat are, for the most part, incorrect.; The last chapter focuses on collagen, another major protein in connective tissues. Here, we focus on developing a novel and general method to study mutations in collagen. In particular, structural aspects of the Arg618Gln mutation in Type I collagen, which causes a Marfan's syndrome-like genetic disorder are discussed. Two model peptides with the wild-type and mutant sequence are designed and expressed. Preliminary structural characterization by NMR (solution and solid state), circular dichroism, and ultra-centrifugation are described.