Soluble derivatives of feather keratin. 1. Isolation, fractionation and amino acid composition

Abstract

G. A. JACOBY 1964 2. There is a lag in growth and oxygen uptake on transferring cells from growth on glucose to an amino acid medium during which the enzymes for amino acid catabolism are formed. 3. In the presence of glucose, or any of a variety of alternative energy sources, adaptation for amino 'acid breakdown is repressed. 4. The effect of glucose on the induction of individual enzymes in the catabolic pathways of tyrosine and histidine has been measured with cellfree extracts. 5. p-Hydroxyphenylpyruvate hydroxylase and homogentisate oxygenase, the second and third enzymes of tyrosine degradation, are repressed by glucose, but tyrosine transaminase, the first enzyme, is neither induced by tyrosine nor repressed by glucose. 6. Histidase and urocanase, the first enzymes in the histidine pathway, are repressed by glucose. 7. Utilization of tyrosine or histidine by fully adapted cells is not decreased in the presence of glucose or other metabolic repressors except acetate. 8. Induction and repression of amino acid oxidation are complementary control mechanisms by which the large enzymic potential of this organism is regulated. I am indebted to Dr J. Mandelstam for valuable criticism and advice. This investigation was supported by a U.S. Public Health Service fellowship (no. EPD-18 124) from the National Institute of Allergy and Infectious Diseases. we have found that 8m-urea is not necessary for solution of the protein. The percentage of protein dissolved was determined from the dry weights of the washed residues. Studies on the effect of temperature on the rate of solution gave results almost identical with the first method, i.e. an activation energy of about 13 kcal./mole. The procedure adopted to prepare soluble proteins was as follows: two solutions, containing (i) CuSO4 (01M) plus NH3 (0-5N), Vol. 92 9

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

“…Table 4 lists the purification procedures developed to obtain keratin derivatives. For a-keratinous materials, reduction, oxidation and sulfitolysis methods have been used to generate satisfactory amounts of the derivatives [16,[64][65][66][67]; while for b-keratinous materials, which have not been as extensively investigated as a-keratin, alkaline thioglycollate and a combination of a disulfide bond-breaking reagent and a protein denaturant were described in literature [68,69]. There are also reports discussing degraded keratins produced by partial hydrolysis (with acid, alkali or enzymes) of wool, hair and feathers.…”

“…Reduction: by potassium thioglycollate in urea to obtain 80-97% keratin from horn, hoof, hair, and further by starch-gel electrophoresis into high-sulfur and lowsulfur fractions [16,64,65] Alkaline thioglycollate [68]: by sodium thioglycollate in the absence of oxygen at PH 11 to obtain 80-90% feather keratin [69] Oxidation: By treating wool with peracetic acid and dilute alkali [66] Combination of a disulfide bond-breaking reagent and a protein denaturant Sulfitolysis: By sodium bisulfite with urea and an oxidizing agent [67] in feather rachis may be correlated with the lack of helical secondary structure. Both exhibit very low content of histidine and methionine.…”

Investigation into Physical and Mechanical Properties of Few Selected Chicken Feathers Commonly Found In Nigeria

“…[3], [4]. Keratin consists of amino acids but largely made up of crytine, lysine, proline and serine [5], [6]. These amino acids tends to cross-link with one another by forming disulphide or hydrogen bonds resulting in fibres that are tough, strong, light weight and with good thermal and acoustic insulating properties [4], [7].…”

Age and Gender Dependent Nutrient Composition of Feather and Feather-Free Body Fractions in Meat-Type Chickens

“…About 85% -90% of the total feather protein is feather keratin, a durable fibrous scleroprotein [11]. According to earlier reports [12] [13] [14] [15], scleroproteins in feathers, hairs, wool and horn contain a high percentage of N (15.0% to 16.8%). Due to our current results, in few days old birds the CP content in the feather DM may even exceed 100% when the common calculation factor (N × 6.25) is applied.…”