scholarly journals Structural studies on the microfibrillar proteins of wool. Interaction between α-helical segments and reassembly of a four-chain structure

1983 ◽  
Vol 209 (3) ◽  
pp. 587-595 ◽  
Author(s):  
L C Gruen ◽  
E F Woods
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Chain Complex ◽  
Alpha Helix ◽  
Chain Structure ◽  
Urea Solution ◽  
Type I ◽  
Type Ii ◽  
Difference Spectra ◽  
Alpha Keratin

The alpha-helix-rich particle of Mr 50 200, derived by limited alpha-chymotryptic digestion of the solubilized microfibrillar proteins from wool alpha-keratin, consists mainly of polypeptide-chain segments of Mr 12 500 (fraction ChC) and 25 000 (fraction ChB). The 12 500-Mr segments are of two types (I and II), which are derived from different polypeptide chains of the microfibrillar complex. Each of these type-I and type-II segments partially self-associates in benign solvents to form either dimers or tetramers. When mixed, the two segments show changes in physical properties (alpha-helix content, difference spectra and molecular weight) indicative of complex-formation. The maximum changes occur when the two segments are mixed in an equimolar ratio. Complexes isolated after rapid dialysis of mixtures from 8 M-urea solution were examined by various methods. A tetrameric structure is the main product formed in all cases, and the maximum amount of tetramer is obtained from equimolar mixtures of the type-I and type-II polypeptides. When urea is removed by dialysis from the unfractionated 12 500-Mr segments (fraction ChC) or from the alpha-helix-rich particle itself, a similar complex of Mr 50 000 is formed. The physical properties of these reconstituted entities (alpha-helix content, molecular weight, thermal stability and exposure of tyrosine residues) are similar to those of the original alpha-helix-rich particle. Cross-linking experiments with dimethyl suberimidate are in agreement with a four-chain complex for the reassembled structures. A pair of double-stranded alpha-helices is proposed for the particle, and is considered to be an integral part of the microfibrillar complex in wool alpha-keratin.

scholarly journals The Type II Deiodinase Is Retrotranslocated to the Cytoplasm and Proteasomes via p97/Atx3 Complex

2013 ◽  
Vol 27 (12) ◽  
pp. 2105-2115 ◽  
Author(s):  
Rafael Arrojo e Drigo ◽  
Péter Egri ◽  
Sungro Jo ◽  
Balázs Gereben ◽  
Antonio C. Bianco
Keyword(s):  
Molecular Weight ◽  
Endoplasmic Reticulum ◽  
Thyroid Hormone ◽  
High Molecular Weight ◽  
20S Proteasome ◽  
Type I ◽  
Type Ii ◽  
Cell Models ◽  
Natural Substrate ◽  
Iodothyronine Deiodinase

The type II iodothyronine deiodinase (D2) is a type I endoplasmic reticulum (ER)-resident thioredoxin fold-containing selenoprotein that activates thyroid hormone. D2 is inactivated by ER-associated ubiquitination and can be reactivated by two ubiquitin-specific peptidase-class D2-interacting deubiquitinases (DUBs). Here, we used D2-expressing cell models to define that D2 ubiquitination (UbD2) occurs via K48-linked ubiquitin chains and that exposure to its natural substrate, T4, accelerates UbD2 formation and retrotranslocation to the cytoplasm via interaction with the p97-ATPase complex. D2 retrotranslocation also includes deubiquitination by the p97-associated DUB Ataxin-3 (Atx3). Inhibiting Atx3 with eeyarestatin-I did not affect D2:p97 binding but decreased UbD2 retrotranslocation and caused ER accumulation of high-molecular weight UbD2 bands possibly by interfering with the D2-ubiquitin-specific peptidases binding. Once in the cytosol, D2 is delivered to the proteasomes as evidenced by coprecipitation with 19S proteasome subunit S5a and increased colocalization with the 20S proteasome. We conclude that interaction between UbD2 and p97/Atx3 mediates retranslocation of UbD2 to the cytoplasm for terminal degradation in the proteasomes, a pathway that is accelerated by exposure to T4.

scholarly journals Amino acid sequences of α-helical segments from S-carboxymethylkerateine-A. Complete sequence of a type-II segment

1978 ◽  
Vol 173 (2) ◽  
pp. 365-371 ◽  
Author(s):  
W G Crewther ◽  
A S Inglis ◽  
N M McKern
Keyword(s):  
Amino Acid ◽  
Coiled Coil ◽  
Complete Sequence ◽  
Amino Acid Sequences ◽  
Helical Axis ◽  
Type I ◽  
Type Ii ◽  
Coil Structure ◽  
Aqueous Urea ◽  
Alpha Keratin

1. The helical fragments obtained by partial chymotryptic digestion of S-carboxymethylkeratine-A, the low-sulphur fraction from wool, were fractionated into type-I and type-II helical segments in aqueous urea under conditions limiting carbamoylation. 2. The amino acid sequence of a 109-residue type-II segment was completed by using the sequenator. 3. When the data were incorporated into a helical model of 3.6 residues per turn the hydrophobic residues generated a band aligned at a slight angle to the helical axis. This result is in accord with the postulated coiled-coil structure of the crystalline regions of alpha-keratin.

scholarly journals Impact assessment of interlayers on geological storage of carbon dioxide in Songliao Basin

2019 ◽  
Vol 74 ◽  
pp. 85 ◽  
Author(s):  
Deping Zhang ◽  
Chengkai Fan ◽  
Dongqin Kuang
Keyword(s):  
Physical Properties ◽  
Songliao Basin ◽  
Type I ◽  
Type Ii ◽  
Geological Storage ◽  
Storage Efficiency ◽  
Reservoir Prediction ◽  
Injection Volume ◽  
Sand Body ◽  
Cap Rock

Reservoirs in the Songliao Basin are characterized by strong heterogeneity, which increases the difficulty of exact reservoir prediction. The clay interlayer developed in the reservoir is an important factor affecting the heterogeneity of the reservoir. Using the reservoir numerical simulation technology, an attempt has been made to investigate the storage efficiency during CO2 sequestration in Songliao Basin considering different types of interlayer in underground formations. Results indicate that type I interlayer, with a large thickness embedded between the two sand bodies has function of shunting and blocking to alleviate the impacts on cap rock. The type II interlayer has a small thickness and locates inside a single sand body, with poor physical properties and continuity, which has the same blocking effect on CO2 distribution and moderating influence on the cap rock. The physical properties of type III interlayer are same as the type II interlayer, but it has uneven distribution and poor continuity. In addition, three schemes of perforated zone were designed and their effects on CO2 storage efficiency and stability were studied. For a single reservoir, the scheme I is to perforate a whole reservoir, which is more conducive to maintain the reservoir’s stability. For multiple sets of “single-reservoir”, the scheme II can be preferentially selected to perforate the reservoir section below the interlayer when the injection volume is small. However, the scheme III can be used to perforate the interlayer and the reservoir below that when the injection volume is large. The study is beneficial to provide guidance and advice for selecting a suitable CO2 geological storage and reduce the risk of CO2 leakage.

Carbon Fibre Reinforced Ultra-High Molecular Weight Polyethylene for Medical Application

1977 ◽  
Vol 6 (4) ◽  
pp. 123-124 ◽  
Author(s):  
J S Bradley ◽  
E J Evans
Keyword(s):  
Molecular Weight ◽  
Composite Material ◽  
High Molecular Weight ◽  
Medical Application ◽  
Flexural Properties ◽  
Type I ◽  
Type Ii ◽  
Carbon Fibres ◽  
Compression Moulding ◽  
Ultra High Molecular Weight

Ultra-high molecular weight polyethylene (UHMWPE) has been reinforced with type I and type II carbon fibres by a compression moulding technique. The composite is found to have markedly improved tensile and flexural properties, suggesting that it would be useful both as an improvement to current polyethylene components and as an inducement to more elaborate designs using the composite material.

scholarly journals Amino acid sequences of α-helical segments from S-carbosymethylkerateine-A. Complete sequence of a type-I segment

1978 ◽  
Vol 173 (2) ◽  
pp. 373-385 ◽  
Author(s):  
K H Gough ◽  
A S Inglis ◽  
W G Crewther
Keyword(s):  
Amino Acid ◽  
Sequence Data ◽  
Coiled Coil ◽  
Alpha Helix ◽  
Protein S ◽  
Amino Acid Sequences ◽  
Type I ◽  
Type Ii ◽  
Sequencing Data ◽  
Helical Segment

The amino acid sequence of a type-I helical segment from the low-sulphur protein (S-carboxymethylkerateine-A) of wool was determined by combining automatic and manual-sequencing data. Whereas in the type-II helical segment most of the cationic groups occur in pairs, 11 of the 22 anionic residues in the sequence of the type-I segment were situated next to a second anionic residue. This suggests possible interactions between type-I and type-II helical segments in alpha-keratin. As observed with the sequence of a type-II helical segment a model constructed on 3.6 residues per turn of helix shows a line of hydrophobic residues along the helix, thereby supporting the physicochemical evidence that the molecule is predominantly helical and forms part of a coiled-coil structure. Examination of the sequence data by predictive methods indicates the possibilty of extensive sections of alpha-helix interspersed with discontinuities. The molecule contains a number of regions with peptide sequences identical with those found by other workers after enzymic digestion of fractions from oxidized wool.

The photolysis of polymethylvinylketone. I. Reactions and kinetics

1955 ◽  
Vol 233 (1193) ◽  
pp. 153-172 ◽  
Keyword(s):  
Molecular Weight ◽  
Ultra Violet ◽  
Type I ◽  
Type Ii ◽  
Weight Changes ◽  
Violet Light ◽  
Aliphatic Ketones ◽  
Primary Reactions ◽  
Acetyl Radical ◽  
Kinetics Of

The photolysis of polymethylvinylketone has been studied in solution. The two primary reactions which occur upon absorption of a quantum of ultra-violet light by the carbonyl group have been shown to be similar to those which occur with simple aliphatic ketones; namely, the type I split to form a polymer radical and a free methyl or acetyl radical, and the type II split at the C—C linkage α — β to the carbonyl which results in a decrease in the molecular weight of the polymer and the formation of a double bond. The kinetics of the molecular weight changes have been followed by viscosity, osmotic pressure and ultracentrifuge measurements on the degraded polymers, and it is shown that these can be explained on the basis of a competing reaction which opposes the breakdown by type II. A mechanism is proposed for this reaction which involves a ‘repolymerization’ due to the addition of free radicals to the double bonds formed by type II.

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