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D A Parry

Publications and source records attributed to D A Parry.

At least 109 records · Page 6Linked to original sources
PubMed1984

The complete cDNA and deduced amino acid sequence of a type II mouse epidermal keratin of 60,000 Da: analysis of sequence differences between type I and type II keratins.

We present the complete nucleotide and deduced amino acid sequences of a mouse epidermal keratin subunit of 60,000 Da. The keratin possesses a central alpha-helical domain of four tracts (termed 1A, 1B, 2A, and 2B) that can form coiled-coils, interspersed by short linker sequences, and has non-alpha-helical terminal domains. This pattern of secondary structure is emerging as common to all intermediate filament subunits. The alpha-helical sequences conform to the type II class of keratins. Accordingly, this is the first type II keratin for which complete sequence information is available, and thus it facilitates elucidation of the fundamental distinctions between type I and type II keratins. It has been observed that type I keratins are acidic and type II keratins are neutral--basic in charge. We suggest that the basis for this empirical correlation between type and charge resides in the respective net charges of the 1A and 2B tracts. Calculations on interchain interactions between charged residues in the alpha-helical domains indicate that this keratin prefers to participate in dimers according to an in-register parallel arrangement. The terminal domains of this keratin possess characteristic glycine-rich sequences, and the carboxyl-terminal domain is highly homologous to that of a human epidermal keratin of 56,000 Da. According to the hypothesis that end-domains are located on the periphery of keratin filaments, we conclude that the corresponding mouse and human keratins are closely related, both structurally and functionally.

Amino Acid Sequence↗
PubMed1984

Collagen fibril diameters and glycosaminoglycan content of skins--indices of tissue maturity and function.

Samples of anatomically and functionally distinct regions of the skin of a variety of altricial and precocial animals were taken at various stages of development from birth to beyond maturity. The glycosaminoglycan (GAG) content and composition of the tissues were determined by chemical analysis and the collagen fibril diameters measured by transmission electron microscopy. The fibril diameters of the skins of two fish and a bird were also assessed for comparison. Analysis and comparison of the data collected show that there was a significant correlation between collagen fibril diameter distribution, GAG type and amount, and functional load-bearing of the various skins, and that the variations in the biochemical and physical composition of the tissues at different stages of development could be related to both their post-conceptual maturity and their prospective functional loading.

Actin Cytoskeleton↗
PubMed1983

Structural homology between hard alpha-keratin and the intermediate filament proteins desmin and vimentin.

Although it has been assumed that the microfibrils in hard -keratin are members of the class of structures known as intermediate filaments (IF), no firm chemical evidence relating the low-sulfur proteins in hard -keratin to other IF proteins has yet been published. We now present primary sequence data for two components from wool keratin which show striking similarities with two IF proteins, desmin and vimentin. The sequences show marked homology, a heptad repeat and a 9.5-residue periodicity in the linear disposition of the acidic and the basic residues. These data thus provide the first evidence that the low-sulfur proteins in hard -keratin and the other IF proteins do indeed have both a similar structure and a common evolutionary origin.

Amino Acid Sequence↗
PubMed1983

Secondary structure of bovine beta-lactoglobulin B.

Secondary-structure-prediction algorithms have been used to find the segments of beta-lactoglobulin sequence most likely to fit the circular dichroism assignment of 15% alpha-helix, 50% beta-sheet, and 15-20% reverse turn. A number of segments may have an alpha-helical conformation but the most prominent region of alpha-helix is from residue 129 to 143. A further probable alpha-helix segment is residues 65-76. The number of residues predicted to occur in segments of beta-sheet structure is less than expected. However, the most likely segments are for residues 1-6, 11-16, 39-45, 80-85, 92-96, 101-107, 117-123, and 145-151. Predicted reverse-turn tetrapeptides are residues 7-10, 49-52, 61-64, 88-91, and 112-115. These predicted secondary structures are consistent with the low-resolution structure of the molecule determined by X-ray diffraction studies.

Amino Acid Sequence↗
PubMed1982

A role for glycosaminoglycans in the development of collagen fibrils.

Extensive data on the glycosaminoglycan (GAG) composition and the collagen fibril diameter distribution have been collected for a diverse range of connective tissues. It is shown that tissues with the smallest diameter collagen fibrils (mass-average diameter less than 60 nm) have high concentrations of hyaluronic acid and that tissues with the largest diameter collagen fibrils (mass-average diameter approximately 200 nm) have high concentrations of dermatan sulphate. It is suggested that the lateral growth of fibrils beyond a diameter of about 60 nm is inhibited by the presence of an excess of hyaluronic acid but that this inhibitory effect may be removed by an increasing concentration of chondroitin sulphate and/or dermatan sulphate. It is also postulated that high concentrations of chondroitin sulphate will inhibit fibril growth beyond a mass-average diameter of approximately 150 nm. Such an inhibition may in turn be removed by an increasing concentration of dermatan sulphate such that it becomes the dominant GAG present in the tissue.

Aging↗
PubMed1982

Coiled-coils in alpha-helix-containing proteins: analysis of the residue types within the heptad repeat and the use of these data in the prediction of coiled-coils in other proteins.

Portions of the amino acid sequences of four representative proteins containing alpha-helices arranged in a coiled-coil rope-like structure have been analysed in terms of the preference of the residues or residue types for specific positions within the observed heptad repeats. The results clearly show an asymmetric distribution of residues which can be interpreted in terms of the size and shape of the residue, the geometry of the coiled-coil structure, or the facility with which interchain or intermolecular interactions may be made. The statistical data reported here may also be used to predict regions of coiled-coil structure in other proteins.

Amino Acid Sequence↗
PubMed1981

Growth and development of collagen fibrils in immature tissues from rat and sheep.

The collagen fibril diameter distribution of four immature tissues from both rat and sheep have been determined from the transverse sections observed in the transmission electron microscope. In many instances before birth, the form of the distribution for the tissues is both unimodal and sharp and the mean diameters of the distributions lie close to a multiple of 80 A. For some tissues, the collagen fibril diameter distributions may be resolved into a number of components, each of which represents a population of fibrils with a diameter close to a multiple of 80 A (8 nm). These data confirm and extend previous observations by the authors that small collagen fibrils growth occurs by the accretion of 80 A units. The form of the collagen fibrils diameter distribution at birth is broad for the sheep tissues but narrow for the rat tissues, thus confirming that the range of fibril diameters at this stage of life reflects the differing degree of development of precocious and altricious animals.

Aging↗
PubMed1979

Electron microscope evidence for an 80 A unit in collagen fibrils.

Connective tissues are composite structures containing collagen, elastin, glycosaminoglycans, minerals, water and other minor components. In all cases the collagen exists predominantly in fibrillar form. The size distribution of the fibrils does, however, vary markedly with both age and the mechanical requirements of the tissue. Little is known about the mechanism of fibril formation in vivo, although some information is now available form in vitro polymerisation studies. We have now collected new and extensive electron microscope data on the size of collagen fibrils from tendon, skin, cornea and other tissues from both fetal and immature animals. The results reported here show that the diameters of the collagen fibrils thus measured lie close to a multiple of 80 A, a result which may be simply and readily interpreted in terms of the collagen microfibril and its mode of packing.

Animals↗