scholarly journals The presence of non-protein nitrogen in acetic acid-soluble calf-skin collagen

1962 ◽  
Vol 83 (2) ◽  
pp. 240-244 ◽  
Author(s):  
FS STEVEN ◽  
GR TRISTRAM
Keyword(s):  
Acetic Acid ◽  
Protein Nitrogen ◽  
Skin Collagen ◽  
Calf Skin

scholarly journals STUDIES ON THE FORMATION OF COLLAGEN

1958 ◽  
Vol 108 (2) ◽  
pp. 215-226 ◽  
Author(s):  
Jerome Gross
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Guinea Pig ◽  
Salt Solution ◽  
Rapid Development ◽  
Neutral Salt ◽  
Salt Solutions ◽  
Pig Skin ◽  
Skin Collagen ◽  
Calf Skin

Precipitation (or gelation) of collagen from cold neutral salt solution induced by warming was shown to be reversible on subsequent cooling. The degree of reversibility of heat precipitation rapidly diminished with time of incubation at 37°C. For calf skin collagen (acetic acid-extracted) and guinea pig skin collagen (crude NaCl extract) in neutral salt solutions (Γ/2 = 0.45) roughly 90 per cent of newly formed gel redissolved on cooling at 2°C.; less than 20 per cent redissolved on cooling gels previously maintained at 37°C. for 24 hours. At physiologic ionic strength the same preparations exhibited much more rapid development of irreversible precipitation, but the same time dependence was clearly evident. Highly purified collagen from crude saline extracts of guinea pig skin exhibited the same phenomenon although the quantitative aspects were somewhat different.

scholarly journals The origin of N-terminal residues in acetic acid-soluble calf-skin collagen

1962 ◽  
Vol 83 (2) ◽  
pp. 245-248 ◽  
Author(s):  
FS STEVEN ◽  
GR TRISTRAM
Keyword(s):  
Acetic Acid ◽  
Skin Collagen ◽  
Calf Skin

scholarly journals The Location of Cross-links in γ Chains from Calf Skin Collagen

1968 ◽  
Vol 243 (11) ◽  
pp. 2890-2898
Author(s):  
M P Drake ◽  
P F Davison
Keyword(s):  
Skin Collagen ◽  
Cross Links ◽  
Calf Skin

scholarly journals The Viscometric Behavior of Solubilized Calf Skin Collagen at Low Rates of Shear

1966 ◽  
Vol 241 (8) ◽  
pp. 1784-1789
Author(s):  
Leo D. Kahn ◽  
Lee P. Witnauer
Keyword(s):  
Skin Collagen ◽  
Calf Skin

The effects of dietary nitrogen level on the collagen of rat skin

1978 ◽  
Vol 39 (1) ◽  
pp. 181-192 ◽  
Author(s):  
R. Dawson ◽  
G. Milne
Keyword(s):  
Crude Protein ◽  
Collagen Content ◽  
Male Rats ◽  
Control Group ◽  
Protein Nitrogen ◽  
Total N ◽  
Dietary Nitrogen ◽  
Low Protein ◽  
Skin Collagen ◽  
Commercial Stock

1. Male rats of approximately 120 g body-weight were maintained on a commercial stock diet containing 204 g crude protein (nitrogen × 6.25)/kg, a hydroxyproline-free high-protein (HP) diet containing 200 g casein/kg as the only protein source, or a low-protein (LP) diet containing 40 g casein/kg. After 6 weeks on these diets half of each group was transferred to a non-protein (NP) diet and the experiment was continued for a further 6 weeks. Animals from each group were killed at 4 d, 3 weeks and 6 weeks after the transfer to the NP diet.2. Throughout the experiment the urinary excretion of N, hydroxyproline and creatinine, and the content and solubility of the skin collagen were determined.3. When compared with a control group killed at the beginning of the experiment the rats maintained on the LP diet showed an increase of 25% in total N content of the skin but collagen content increased by 100%. Rats transferred from the HP to the NP diet lost both N and collagen from the skin, but those transferred from the LP to the NP diet lost N but increased the collagen content by 42%.4. Protein deprivation brought about marked changes in the solubility of the skin collagen, suggesting an increase in the rate of maturation of skin collagen.

Determination of Protein Nitrogen in Plants

1977 ◽  
Vol 60 (3) ◽  
pp. 590-593 ◽  
Author(s):  
T Powell Gaines
Keyword(s):  
Acetic Acid ◽  
Plant Tissue ◽  
Nonprotein Nitrogen ◽  
Protein Nitrogen ◽  
Aoac Method ◽  
The Mean

Abstract A method is described for determining protein nitrogen (PN) in plants. Plant tissue extracted with 0.5% acetic acid to remove nonprotein nitrogen (NPN) prior to Kjeldahl analysis gave results very close to true PN, whereas AOAC crude PN method 2.049 gave results much too high. True PN was determined as the mean of 3 independently derived values and was used as the basis for comparing the proposed PN method with AOAC method 2.049. Failure of the AOAC method to differentiate between NPN and/or inorganic ammoniacal N and actual PN causes values derived from this method to be too high when it was used to determine PN in plants.

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