imilar to that of the family c-type lysozymes which are naturally 1702259-66-2 occurring glycosidases involved in the degradation of bacterial cell walls. The protein interior is almost entirely hydrophobic while both charged amino acid residues and non-polar patches cover its interface. Small molecules easily intermingled with protein molecules as PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19729111 well as to the solvent medium that make them the most fascinating agents for inhibiting amyloid formation. One such molecule is D-cycloserine, a cyclic structural analogue of D-alanine, chosen in present study as one of the 
test drug molecule as it act as partial agonist at the glycine recognition site of the glutamatergic NMDA receptor and can boost extinction learning in animals. Furthermore, it also affect non-spatial reference memory in a similar manner as shown for spatial reference memory in rats. Thus, although originally designed to be anti-tuberculosis agent, DCS was later used as a potential treatment for Alzheimer’s dementia and negative symptoms in Schizophrenia. The second chosen anti tuberculosis drug molecule for present study is pyrazinamide which is a nicotinamide analog. Recently, nicotinamide reported as anti-amyloidogenic agent in ex-vivo study and also suppresses tau mediated neurodegeneration in Drosophila model. Thus, the aim of the present study was to provide a detailed understanding of the in-vitro inhibition mechanism of fibrillation in HEWL influenced by the test small drug molecules i.e., DCS and PYZ with two different functional groups i.e.,CO andCONH2, respectively. The kinetics of heat-induced amyloid formation in HEWL and then its attenuation by DCS and PYZ was investigated PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19731037 using various spectroscopic and microscopic techniques as well as molecular docking analysis. Materials and Methods Hen egg white lysozyme, Thioflavin T, 1-anilino 8 naphthalene sulphate, Congo red, pyrazinamide and D-cycloserine were purchased from Sigma Chemical Co.. All other reagents used were of analytical grade. Double distilled water was used throughout the study. 2.1. Sample preparation The HEWL was dialyzed in 20 mM sodium phosphate buffer pH 7.4 and its concentration was estimated spectrophotometerically using M = 37970 M-1cm-1. The final concentration of HEWL was kept 10 M and was incubated for 120 h at 65C under constant stirring in absence and presence of different concentrations of PYZ and DCS separately. The A-42 was prepared as described in literature. The final concentration of A-42 was kept 25 M and was incubated for 70 h at 37C under constant stirring in absence and presence of 500M of PYZ and DCS separately. For further analysis, aliquots were taken from each set at different time intervals. The solutions of PYZ and DCS were also made in 20 mM sodium phosphate buffer. Stock solutions for ThT, Congo red and ANS were prepared using 2 / 21 Anti-Amyloid Behavior of Pyrazinamide and D-Cycloserine 1% nm = 36,000 M-1cm-1M498nm = 45,000 M-1 cm-1and 1% nm = 5000 M-1cm-1 respectively 412 350. The pH measurements were carried out on Mettler Toledo pH meter model using Expert “Pro3 in 1” type electrode. 2.2. Turbidity measurement Turbidity measurements of aliquots incubated in absence and presence of drugs were carried on Perkin Elmer Lambda 25 double beam spectrometer at 350 nm in a cuvette of 1 cm path length. The equilibrium data obtained from turbidity measurements was fitted using Sigma plot 12.0 to single exponential equation: A A0 eLI 1 where A0 and A are the turbidities at 350 nm in the
