PubMed Health⌕ Search

Biomedical subjects

J H Waite

Publications and source records attributed to J H Waite.

At least 73 records · Page 4Linked to original sources
PubMed1987

Prolyl 4-hydroxylase in the foot of the marine mussel Mytilus edulis L.: purification and characterization.

The mussel foot secretes a variety of unusual hydroxyproline-containing collagenous and noncollagenous proteins. Prolyl 4-hydroxylase acting on one or more of the secreted proteins was isolated from the foot by using conventional gel filtration and ion exchange chromatography. Mr of the intact enzyme was 230,000 (alpha 2 beta 2) composed of two subunits with Mr of 60,000 (alpha) and 57,000 (beta) as estimated by HPLC gel filtration and SDS-PAGE. The enzyme utilized (Pro-Pro-Gly)10 as a substrate with an apparent Km value of 0.17 mM. Cofactors and inhibitors were very similar to animal, plant, and microbial prolyl hydroxylases previously described. The enzyme had a relatively sharp pH optimum in the range of 7.8-8.3 and the hydroxyproline formed increased in proportion to the rise in the temperature between 5 and 20 degrees C. No detectable hydroxylation occurred with poly-L-proline or the unhydroxylated decapeptide analog (Ala-Lys-Pro-Ser-Tyr-Pro-Pro-Thr-Tyr-Lys) of the polyphenolic protein. Kinetic studies, however, revealed that the mussel prolyl 4-hydroxylase was competitively inhibited by poly-L-proline and uncompetitively inhibited by the decapeptide. These results suggest that the decapeptide binds the enzyme-substrate i.e. (Pro-Pro-Gly)10 complex. It is not yet clear whether this enzyme acts exclusively on collagenous substrates or whether its catalytic purview extends as well to the polyphenolic protein.

Animals↗
PubMed1986

Optimization of hydroxylation of tyrosine and tyrosine-containing peptides by mushroom tyrosinase.

Free tyrosine and tyrosine residues in various peptides and proteins are converted into dopa and dopa residues by tyrosinase (monophenol,L-dopa:oxygen oxidoreductase, EC 1.14.18.1) in the presence of reductants. The efficiency of the tyrosine-to-dopa conversion was examined under varied conditions, such as the substrate-to-tyrosine ratio, concentrations of reductant and oxygen in the reaction solution, pH, temperature and reaction time. The highest dopa yields were achieved with the following optimal conditions for hydroxylation: 0.1 M phosphate buffer at pH 7, 25 mM ascorbic acid, 1 mM tyrosine, 50 micrograms/ml tyrosinase and 20 degrees C. Using these conditions, up to 70% of free tyrosine was converted into dopa, and tyrosine residues in several synthetic peptides were also hydroxylated to dopa residues at ratios as high as free tyrosine. The preparation of hydroxylated analogues of the decapeptide (Ala-Lys-Pro-Ser-Tyr-Pro-Pro-Thr-Tyr-Lys), in particular, may contribute to a better understanding of adhesion in the dopa-containing mussel glue protein.

Ascorbic Acid↗
PubMed1986

Protein gradients in byssal threads of some marine bivalve molluscs.

Many marine bivalve molluscs produce byssal threads for attachment to solid substrata. Small (less than 10 mm) consecutive sections of the byssal threads of Mytilus edulis, M. californianus, Geukensia demissa, Atrina vexillum, and A. rigida were analyzed by amino acid analysis to determine if chemical composition remains constant as a function of location in thread segments. Nonlinear longitudinal protein gradients, probably involving collagen and an elastic protein, were found in the Mytilus species. In these, collagen peaks in the distal third of the thread. In Geukensia and the Atrina species, although the two differed greatly in composition, there is a clear nonvariability in composition of the thread within each species as a function of location in the thread. The adhesive plaque at the tip of the thread of all species examined differs substantially in composition from the remainder of the thread. Protein gradients in the threads of some bivalves may reflect specific adaptations evolved to respond to exposed habitats in high-energy environments.

Amino Acids↗
PubMed1986

Location and analysis of byssal structural proteins of Mytilus edulis.

The acellular attachment organ (byssus) of the marine mussel Mytilus edulis L. is composed of threads that emanate from the body of the mussel to adhesive discs that anchor the threads to rocks, sand and other mussels. Three proteins have been purified by immunohistological methods and located to specific regions of the byssus. A collagenous protein with subunit molecular weights of 53,000, 55,000 and 65,000 is found in the matrix of the elastic thread region. Its 73,000-MW precursor was extracted from foot glands in the area proximal to the animal body and was identified by immune cross-reactivity. A cystine-rich, acidic protein was found in all regions of the byssus associated with a third protein, the polyphenolic protein. The L-dopa-containing polyphenolic protein appears in the cortex of the entire thread and adhesive plaque and at the substrate-plaque interface. Antiserum to this protein stains spherical vesicles in the phenol gland of the foot. Using immuno-electrophoretic methods, the polyphenolic protein and the cystine-rich protein were shown to form high molecular weight aggregates with aging of the byssus.

Amino Acids↗
PubMed1986

Composition and ultrastructure of the byssus of Mytilus edulis.

Three regions of the byssus of the marine mussel Mytilus edulis L. are distinct in structural organization at the macroscopic and microscopic level and in amino acid composition. The threads that emanate from the stem at the base of the foot are divided into two regions. The proximal, elastic region has a crimped, densely staining cortex enclosing an interior matrix of spiral fibers, and its amino acid composition reflects protein heterogeneity. The more distal, rigid region has a straight, tubular cortex surrounding an inner matrix of linearly arranged bundles of fibrils and has a composition approximating pure collagen. The plaque, or disc-shaped portion, which mediates attachment to various substrates, is distinguished by a surface matrix of collagen-like fibers similar to those of the thread region and anchored on an inner spongy matrix. Compositional evidence exists for a collagenous component, a catechol-rich protein, and at least one other accessory protein in the plaque.

Amino Acids↗
PubMed1986

Mussel glue from Mytilus californianus Conrad: a comparative study.

Marine mussels secrete a byssus in order to attach to solid surfaces in the sea. The polyphenolic protein is the "glue" in the adhesive plaques of the byssus. In Mytilus californianus, the polyphenolic protein has an apparent molecular weight of 85,000 +/- 5,000 and is rich in the amino acids lysine, 3,4-dihydroxyphenylalanine, serine, threonine, and hydroxyproline. In composition it resembles the polyphenolic protein of M. edulis (Mr = 125,000), although the M. edulis protein contains significantly less isoleucine and more alanine. Tryptic digestion of M. californianus polyphenolic protein revealed two types of repeating decapeptides (1) (Ser/Thr)-Thr-(Tyr/Dopa)-Hyp-Hyp-Thr-Dopa-Lys-Hyp-Lys and (2) Ile-(Thr/Ser)-(Tyr/Dopa)-Hyp-Hyp-Thr-Dopa-Lys-Hyp-Lys. Residues 2 to 8 are identical with residues 4-10 in M. edulis decapeptides.

Amino Acids↗
PubMed1985

Peptide repeats in a mussel glue protein: theme and variations.

The adhesive protein from Mytilus edulis contains 75-80 closely related, repeated peptide sequences in its primary structure. These peptides can be resolved following digestion with trypsin by reversed-phase high-pressure liquid chromatography. The most frequently repeated sequence is the decapeptide Ala-Lys-Pro-Ser-Tyr-Hyp-Hyp-Thr-Dopa-Lys (peptide E). Variations of this occur in peptides B with Hyp-3 and Dopa-5, C with Dopa-5, and D with Hyp-3, respectively. Lesser amounts of hexapeptides (A and B') that are lacking residues 4-7 also occur. Peptide A has the sequence Ala-Lys-Pro-Thr-Dopa-Lys, whereas B' contains Tyr instead of Dopa. 4-Hydroxyproline occurs at positions 3 and 7 and occasionally at position 6 of the decapeptide; 3-hydroxyproline occurs only at position 6. Adhesiveness of the protein may be related to the repetition of Dopa residues, the catecholic moiety of which has strong hydrogen-bonding and metal-liganding capabilities.

Amino Acid Sequence↗
PubMed1983

Evidence for a repeating 3,4-dihydroxyphenylalanine- and hydroxyproline-containing decapeptide in the adhesive protein of the mussel, Mytilus edulis L.

Previous work has shown that the permanent adhesive of the marine mussel Mytilus edulis is a protein containing large amounts of hydroxyproline (13%) and 3,4-dihydroxyphenylalanine (Dopa, 11%). The protein also known as the polyphenolic protein is produced and stored in the exocrine phenol gland of the mussel and deposited onto marine surfaces by the animal's foot during the formation of new adhesive plaques. The adhesive protein has been purified by a combination of ion exchange on sulfonylpropyl-Sephadex and gel filtration on low surface energy chromatographic media. Polyacrylamide gel electrophoresis of the protein at acidic pH shows it to consist of two components having a molecular weight of about 130,000. Treatment of the protein with clostridial collagenase reduced the molecular weight by less than 10%. The collagenase-resistant fragment contains most or all of the Hyp and Dopa. Trypsin treatment of the polyphenolic protein results in extensive degradation. The major tryptic peptide (80%) contains 10 amino acids including Hyp and Dopa and was shown by sequence analysis to be H2N-Ala-Lys-Pro-Ser-Tyr-Hyp-Hyp-Thr-Dopa-Lys-COOH. Calculations suggest that this and related sequences may be repeated as often as 75 times in the polyphenolic protein.

Amino Acids↗
PubMed1980

Nereis cuticle collagen. Proteolysis by marine vibrial and clostridial collagenases.

Proteolysis of Nereis cuticle collagen by two bacterial collagenases was investigated using viscosimetry, enzyme kinetics, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and ion exchange chromatography of collagenolytic peptides. Collagenase of the marine Vibrio B-30 completely degrades native cuticle collagen at 7 degress C with a turnover number 50 times greater than that of the clostridial collagenase. Although turnover numbers for the two enzymes are comparable when using denatured cuticle collagen as substrate, the vibrial collagenase appears to cleave twice as many peptide bonds per mg of cuticle collagen as does the clostridial enzyme. Sodium dodecyl sulfate gel electrophoresis of collagenase-digested native cuticle collagen reflects the resistance of the collagen to clostridial collagenase; however, the vibrial enzyme completely degrades the cuticle collagen with the formation of one transient intermediate (Mr 400,000). Peptide analysis of fully digested denatured cuticle collagen reveals that the two enzymes have a number of qualitative and quantitative similarities. Despite these, however, only the vibrial collagenase seems capable of extensively degrading native cuticle collagen.

Animals↗
PubMed1977

Thyrotoxicosis and pregnancy. Use of preoperative propranolol for thyroidectomy.

Propranolol has been utilized safely and successfully in the preparation for thyroidectomy in four pregnant patients with thyrotoxicosis. No ill effects were noted in mothers or infants. No change in fetal heart function was noted while two mothers were receiving propranolol. The major advantage of propranolol over the thiourea drugs is the rapidity with which the patient can be prepared for operation. Preparation with beta blockage can be accomplished in five to ten days. This limited experience suggests that propranolol is probably the drug of choice for preparation of the gravid thyrotoxic patient for whom thyroidectomy is planned.

Adult↗