Ramakrishnan Nagaraj

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Structure and biological activities of synthetic peptides corresponding to bovine neutrophil beta-defensin BNBD-12, GPLSC(1)GRNGGVC(2)IPIRC(3) PVPMRQIGTC(4) FGRPVKC(5) C(6)RSW with disulfide connectivities C(1)-C(5), C(2)-C(4) and C(3)-C(6) and its variants with one, two and three disulfide bridges have been investigated. Selective protection of cysteine(More)
The antibacterial activity of human neutrophil defensin HNP-1 analogs without cysteines has been investigated. A peptide corresponding to the HNP-1 sequence without the six cysteines (HNP-1deltaC) exhibited antibacterial activity toward gram-negative and gram-positive bacteria. Truncated analogs wherein the nine N-terminal residues of HNP-1 and the(More)
Delta-Lysin is a 26-residue hemolytic peptide secreted by Staphylococcus aureus. Unlike the bee venom peptide melittin, delta-lysin does not exhibit antibacterial activity. We have synthesized delta-lysin and several analogs wherein the N-terminal residues of the toxin were sequentially deleted. The toxin has three aspartic acids, four lysines and no(More)
The antibacterial activities of synthetic human beta-defensin analogs, constrained by a single disulfide bridge and in the reduced form, have been investigated. The peptides span the carboxy-terminal region of human beta-defensins (HBD-1-3), which have a majority of cationic residues present in the native defensins. The disulfide constrained peptides(More)
Synthetic peptides Phd1-3 spanning the cationic carboxy-terminal region of human beta-defensins HBD-1-3 have been shown to have antibacterial activity. Gross morphological changes were seen in E. coli cells treated with these peptides. In this paper, we have studied the surface-active properties of peptides Phd1-3 and their interactions with different(More)
We have examined the antimicrobial activity of C-terminal analogs of human β-defensins HBD-1 and-3 wherein lysines have been selectively replaced by L- and D-arginines and L-isoleucine substituted with its D-enantiomer. The analogs exhibited antibacterial and antifungal activities. Physiological concentration of NaCl did not attenuate the activity of the(More)
Human β-defensins (HBDs) are cationic antimicrobial peptides that are components of the innate immune system. They are characterized by three disulfide bridges. However, the number of cationic residues as well as the presence of lysine and arginine residues vary. In HBD4, the cationic residues occur predominantly in the N-terminal segment, unlike in HBD1-3.(More)
The antibacterial activity of peptides without disulfide bridges, spanning the carboxy-terminal segment of arthropod defensins, has been investigated. Although all the peptides have net positive charges, they exhibited varying antibacterial potencies and spectra. Atomic force and fluorescence microscopic analyses indicate that the peptides exert their(More)
The SH4 domain of Src family of nonreceptor protein tyrosine kinases represents the extreme N-terminal 1–16 amino acid region which mediates membrane association of these proteins and facilitates their functions. The SH4 domains among Src members lack well-defined sequence consensus and vary in the net charge. However, they readily anchor to the cytoplasmic(More)
Alpha helices (AH) are peptide fragments characterized by regular patterns of hydrogen bonding between the carbonyl oxygen and amino nitrogen of residues regularly spaced in sequence, resulting in spiral conformations. Their preponderance in protein structures underlines their importance. Interestingly, AHs are present in most anti-microbial peptides,(More)