Degradation of keratin substrates by keratinolytic fungi

Background: The hydrolysis of keratin wastes by microorganisms is considered a biotechnological alternative for recycling and valorization through keratinolytic microorganisms. Despite their resistant structure, keratin wastes can be efficiently degraded by various microorganisms through the secretion of keratinases, which are promising enzymes for several applications, including detergents, fertilizers, and leather and textile industry. In an attempt to isolate keratinolytic microorganisms that can reach commercial exploitation as keratinase producers, the current work assesses the dynamics of keratin biodegradation by several keratinolytic fungal strains isolated from soil. The activity of fungal strains to degrade keratin substrates was evaluated by SEM, FTRIR-ATR spectra and TGA analysis. Results: SEM observations offered relevant information on interactions between microorganism and structural elements of hair strands. FTIR spectra of the bands at 1035­1075 cm-1 assigned to sulfoxide bond appeared because of S­S bond breaking, which demonstrated the initiation of keratin biodegradation. According to TGA, in the second zone of thermal denaturation, where keratin degradation occurs, the highest weight loss of 71.10% was obtained for sample incubated with Fusarium sp. 1A. Conclusions: Among the tested strains, Fusarium sp. 1A was the most active organism in the degradation process with the strongest denaturation of polypeptide chains. Because keratinolytic microorganisms and their enzymes keratinases represent a subject of scientific and economic interest because of their capability to hydrolyze keratin, Fusarium sp. 1A was selected for further studies.

Antigen-binding Characteristics of Circulating IgG Autoantibodies to Cytokeratin 18 Protein in Patients with Nonallergic Asthma

Cytokeratin 18 (CK18) protein was identified as an airway epithelial cell autoantigen associated with nonallergic asthma. Cleavage of CK18 protein by caspase-3 is a marker of early apoptosis in epithelial cells. It has been shown that the expression of active caspase-3 was increased in bronchial epithelial cells of asthmatic patients, when compared with healthy controls. To investigate the antigen-binding characteristics of IgG autoantibodies to CK18 protein in nonallergic asthma, the bindings of IgG autoantibodies to the fragments of CK18 protein cleaved by caspase-3 were analyzed by Western blot using serum samples from three patients with nonallergic asthma. Recombinant human CK18 protein was treated by caspase-3 and cleaved into N-terminal fragment (1-397 amino acids) and C-terminal fragment (398-430 amino acids). The binding capacity of IgG autoantibodies to N-terminal fragment of CK18 was maintained in one patient and reduced in other two patients. IgG autoantibodies from all three patients did not bind to C-terminal fragment of CK 18. In conclusion, IgG autoantibodies to CK18 protein from patients with nonallergic asthma seems to preferentially bind to the whole molecule of CK18 protein and their antigen-binding characteristics were heterogeneous among the patients with nonallergic asthma.

Circulating Autoantibodies in Patients with Aspirin-intolerant Asthma: An Epiphenomenon Related to Airway Inflammation

Several studies have suggested the involvement of an autoimmune mechanism in aspirin (ASA)-intolerant asthma. To test this hypothesis, we measured the levels of circulating autoantibodies, such as IgG and IgA to tissue transglutaminase (TGase), IgG to cytokeratins (CKs) 8, 18, and 19, Clq-binding immune complex (CIC), and antinuclear antibody (ANA), in the sera of 79 patients with ASA-intolerant asthma (Group I) and those of two control groups, consisting of 61 patients with ASA-tolerant asthma (Group II) and 88 healthy control subjects (Group III) by means of ELISA. Significantly higher prevalences of IgG antibodies to CK18 (13.9%) and CK19 (17.7%) were noted in Group I, as compared with Group III (p<0.05 for all) not with Group II. Regarding the prevalences of other autoantibodies, the levels of ANA (1.3%), IgG to TGase (3.8%), and CIC (24.7%) in Group I were not significantly different from those in Groups II and III. Significant correlations were found between positivities for the anti-CK18 and anti-CK19 autoantibodies and the PC20 methacholine values in the analysis of asthma Groups I and II vs. normal controls, (p=0.001 and p=0.003, respectively). Further studies are needed to explore the potential involvement of an autoantibody-mediated mechanism in the clinical manifestation of bronchial asthma.

Molecular characterization of hair cuticle and its extracted proteins in seven mammalian species

Hair is an of the epidermis in mammals and consists of two large groups of human hair proteins. One is hard -keratins and the other is matrix proteins. The present investigation aimed to compare the ultrastructural of the hair scale using the scanning electron microscope, and the proteins and amino acids content of the keratin in seven mammalian species. The values of the hair thickness, x/y feret and hair pattern of the species in the present study confirm the presence of species-specific characteristics and ultra structural variation. The situation in man differs from the wild mammals due to damage of hair cuticle caused by mechanical abuse, exposure to ultraviolet radiation and chemical over processing. The maximum amount of extracted proteins from hair keratin was analyzed by SDS-PAGE. The electrophoretic patterns showed an overall degree of similarity. However, differences exist between species in the intensity of stain. Quantitatively, the electrophoretic patterns scanned and analyzed using gel protein analyzer. The results showed no difference between the molecular mass of some species, but different in molecular mass distribution. Amino acid composition of keratin of mammalian hair species of the present study showed some variation, especially for methionine, isoleucine, lysine and arginine. The other amino acids studied are significantly present in most hair. One of the later amino acid is cysteine. Cysteine is a very important due to the presence of disulfate cross-links

Electrophoretic variation of hair proteins

Hair follicle cells secrete a complex assortment of proteins that form the hair shaft, and can be classified into two major groups. The lowsulfur proteins are keratins that contribute to the backbone of intermediate filaments, and the high-sulfur proteins are associated with these filaments. In the present investigation we describe a comparative electrophoretic study of normal human hair proteins from 182 individuals, including some families. Hair proteins were extracted in urea buffer (pH 9.3), examined by 1O per cent polyacrylamide gel electrophoresis (pH 8.8) in the presence of sodium dodecyl sulfate and stained with Coomassie brilliant blue. Eighteen bands appeared and were reproducible in most individuals, with apparent molecular mass ranging from 10.0 to approximately 100 kDa. Based on the most prominent bands, an electrophoretic profile defined as the "frequent profile" was observed. This profile was observed in 180 individuais and consisted of 6 prominent bands, 4 of them of apparent molecular mass in the 407O-kDa range, which is characteristic of keratins (61.9 ñ 1.02, 58.5 ñ 1.21, 47.9 ñ 1.58, and 45.4 ñ 1.53 kDa), and 2 bands with lower molecular mass (18.9 ñ 0.75 and 13.7 ñ 0.91 kDa). In 2 samples from unrelated women, an additional band of 42.1 ñ 1.72 kDa appeared. The meaning of this variant is still under investigation.