scholarly journals The Structure of Surface-Denatured Protein. II. Relation between the Surface Diffusion Constant and the Shape of the Protein Molecule (Theoretical)

1952 ◽  
Vol 25 (1) ◽  
pp. 10-13
Author(s):  
Kazutomo Imahori
Keyword(s):  
Surface Diffusion ◽  
Diffusion Constant ◽  
Protein Molecule ◽  
Denatured Protein

Scaling Description of Sub-Monolayer Epitaxial Growth

1992 ◽  
Vol 280 ◽  
Author(s):  
A. Zangwill
Keyword(s):  
Epitaxial Growth ◽  
Surface Diffusion ◽  
Diffusion Constant ◽  
Current Status ◽  
Future Research ◽  
Deposition Flux ◽  
Simple Relationship ◽  
Island Nucleation ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy

ABSTRACTRecent experimental results aimed at the measurement of surface diffusion constants by use of scanning tunnelling microscopy and diffraction techniques have reawakened interest in the statistical properties of two-dimensional island nucleation and growth in the submonolayer regime. Classical homogeneous rate equation studies published over twenty years ago established a simple relationship among the number density of stable islands, the deposition flux, and the adatom surface diffusion constant. Recent Monte Carlo simulation studies confirm this prediction and considerably extend the scope of such a scaling description of submonolayer epitaxial growth. In this article, I review the current status of theory and experiment in this area and suggest some areas for future research.

The Relationship of Properties of Synthetic Poly(Isoprene) and Natural Rubber in The Factory. The Effect of Non-Rubber Constituents of Natural Rubber

1973 ◽  
Vol 46 (1) ◽  
pp. 47-66 ◽  
Author(s):  
E. C. Gregg ◽  
J. H. Macey
Keyword(s):  
Natural Rubber ◽  
Protein Molecule ◽  
Insoluble Fraction ◽  
Prosthetic Group ◽  
Rubber Material ◽  
Green Strength ◽  
Denatured Protein ◽  
Low Concentrations ◽  
Relationship Of ◽  
The Relationship

Abstract The causes of some of the differences in properties between compounded natural rubber and compounded synthetic poly (isoprene) have been traced to the insoluble non-rubber material in natural rubber. This material is mostly denatured proteins and is responsible for the higher modulus, faster scorch time, higher heat buildup, and higher hot tear strength of natural rubber. These properties may be related to the pigment effect of the denatured protein to act as a reinforcing filler at low concentrations (3–4 per cent by wt) as well as a curing activator. The greater green strength of compounded natural rubber has been related to its more perfect configurational regularity which contributes to faster crystallization. The crystallite concentration increases with increasing stress and the crystallites act like a reversible reinforcing pigment which disappears when the stress is released. The faster plastication rate has been related to the synthetic stabilizers used. Natural rubber hydrocarbon has been shown to be a high molecular lactone arranged in a six membered ring. We speculate natural rubber forms as a prosthetic group connected through a lactone linkage (or the δ-hydroxy acid precursor to the lactone) to a protein molecule in the cell of hevea brasiliensis. It is this structure of a high molecular weight hydrocarbon (natural rubber) attached to a (denatured) protein molecule that accounts for the remarkable dispersability of the insoluble fraction of natural rubber in rubber solvents : the rubber end of the structure tends to dissolve in the rubber solvent while the highly polar, insoluble protein end prevents solution. This structure is the reverse of a micelle in water in principle.

Inhibition of Ribonuclease Activity by Bentonite

1973 ◽  
Vol 51 (11) ◽  
pp. 1558-1565 ◽  
Author(s):  
G. G. Jacoli ◽  
W. P. Ronald ◽  
L. Lavkulich
Keyword(s):  
Cation Exchange Capacity ◽  
Protein Molecule ◽  
Exchange Capacity ◽  
Ribonuclease Activity ◽  
X Ray Diffraction ◽  
Tertiary Structures ◽  
Similar Treatment ◽  
X Ray ◽  
Denatured Protein ◽  
Clay Matrix

The inhibition of ribonuclease activity by bentonite and the adsorption of the protein molecule within the clay matrix were assessed by enzyme and X-ray diffraction analysis, respectively.Pretreatment of bentonite with EDTA, potassium, barium, and barium–EDTA caused varying expansion of the d(001) spacing of the clay. The d(001) variation was sensitive to pH.Inhibition of the enzyme activity generally followed the pattern of expansion of the d(001) spacing of the clay, but failed when the interlayers of bentonite expanded beyond their maximum capability.Vermiculite, which is a clay having a higher cation exchange capacity than bentonite, did not expand from the normal state after similar treatment nor did it inhibit ribonuclease activity.When the secondary and tertiary structures of the protein molecule were disrupted, the denatured protein still entered the interlayers of bentonite, but caused a greater expansion of the d(001) spacing than the native ribonuclease.

On the coverage dependence of the surface diffusion constant

1980 ◽  
Vol 99 (3) ◽  
pp. L429-L433
Author(s):  
Hiromu Asada ◽  
Makihiko Masuda
Keyword(s):  
Surface Diffusion ◽  
Diffusion Constant ◽  
Coverage Dependence

On the coverage dependence of the surface diffusion constant

1980 ◽  
Vol 99 (3) ◽  
pp. L429-L433 ◽  
Author(s):  
Hiromu Asada ◽  
Makihiko Masuda
Keyword(s):  
Surface Diffusion ◽  
Diffusion Constant ◽  
Coverage Dependence

Computer Simulation of Surface Diffusion of Silicon and Carbon Adatoms on SiC(001)

1996 ◽  
Vol 423 ◽  
Author(s):  
Q. A. Bhatti ◽  
G. J. Moran ◽  
C. C. Matthai
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Molecular Dynamics Simulations ◽  
Surface Diffusion ◽  
High Temperatures ◽  
Diffusion Constant ◽  
Temperature Dependent ◽  
Adatom Diffusion ◽  
Diffusion Paths ◽  
Dynamics Simulations

AbstractWe have performed molecular dynamics simulations of adatom diffusion on the SiC(001) surface and found that the barriers for carbon adatoms is less than that for silicon adatoms. The diffusion paths were also found to be temperature dependent and at high temperatures the adatom diffusion constant was found to of the order of 10−5 cm2 s−1.

scholarly journals THE EFFECTS OF CATHODE RAYS ON THE PROTEINS OF SERUM

1929 ◽  
Vol 50 (4) ◽  
pp. 439-444
Author(s):  
Lillian E. Baker ◽  
Robert B. Corey
Keyword(s):  
Beneficial Effect ◽  
Isoelectric Point ◽  
Protein Molecule ◽  
Hydrolytic Cleavage ◽  
Trichloracetic Acid ◽  
Characteristic Appearance ◽  
Sh Groups ◽  
Denatured Protein ◽  
Retarding Effect

The effects of cathode rays on the proteins of serum appear to be (1) denaturation of a large proportion of the albumin and globulin with the formation of products that are soluble at the pH of the serum; (2) the production of a tough and exceedingly insoluble substance on the window of the cell where most of the absorption of electrons occurs; (3) a slight hydrolytic cleavage of the protein molecule producing a small quantity of products having properties so near to those of the protein that they are precipitated by trichloracetic acid but are not removed by coagulation at the isoelectric point; (4) the production of a small amount of hydrolytic products not precipitated by trichloracetic acid; and (5) the formation of a small amount of ammonia, part of which at least is derived from the urea in the serum. It is interesting to note that these changes are such as would bring about exactly those effects on fibroblasts which were observed when cultures were grown in serum which had been subjected to cathode ray irradiation. The proteins of serum have a retarding effect on the growth of fibroblasts. We might, therefore, expect their removal by denaturation and coagulation to result in the slightly larger growth which was observed. The production of SH groups in the denatured protein molecule would also tend to have a beneficial effect, as has been observed in experiments with denatured albumin. A concentration of protein split products equal to that in the irradiated sera has been observed to produce cells of characteristic appearance, full of cytoplasmic granulations and possessing long, active pseudopods, such as those noted in colonies cultivated in serum which had been subjected to cathode rays.

scholarly journals SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS

1936 ◽  
Vol 19 (3) ◽  
pp. 427-438 ◽  
Author(s):  
A. E. Mirsky ◽  
M. L. Anson
Keyword(s):  
Serum Albumin ◽  
Quantitative Methods ◽  
Protein Denaturation ◽  
Protein Molecule ◽  
Insoluble Fraction ◽  
Egg Albumin ◽  
Sh Groups ◽  
Denatured Protein ◽  
Hydrolyzed Protein ◽  
Air Water Interface

1. In native egg albumin no SH groups are detectable, whereas in completely coagulated albumin as many groups are detectable as are found in the hydrolyzed protein. In egg albumin partially coagulated by heat the soluble fraction contains no detectable groups, and the insoluble fraction contains the number found after hydrolysis. 2. In the reversal of denaturation of serum albumin, when insoluble protein regains its solubility, S-S groups which have been detectable in the denatured protein, disappear. 3. When egg albumin coagulates at an air-water interface, all the SH groups in the molecule become detectable. 4. In egg albumin coagulated by irradiation with ultraviolet light, the same number of SH groups are detectable as in albumin coagulated by a typical denaturing agent. 5. When serum albumin is denatured by urea, there is no evidence that S-S groups appear before the protein loses its solubility. 6. Protein denaturation is a definite chemical reaction: different quantitative methods agree in estimates of the extent of denaturation, and the same changes are observed in the protein when it is denatured by different agents. A protein molecule is either native or denatured. The denaturation of some proteins can be reversed.

A theory of contamination in electron microscopes by surface diffusion

1978 ◽  
Vol 36 (1) ◽  
pp. 116-117
Author(s):  
J.T. Fourie
Keyword(s):  
Electron Beam ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Physical Parameters ◽  
Carbon Compounds ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Primary Electrons ◽  
Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

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