Amino acid replacements in yeast iso-1-cytochrome c. Comparison with the phylogenetic series and the tertiary structure of related cytochromes c.

Multifunctional Cytochrome c: Learning New Tricks from an Old Dog

“…Moreover, F10 has been implicated in the recognition of the HCCS enzyme, thus pointing out the importance of these residues in assembly and folding of the protein to the native state. ,,− W59 is H-bonded to one of the heme propionates, which along with the hydrophobic character of its side chain is thought to strongly modulate the electrostatic environment of the heme. , Y67 participates in an extensive redox-sensitive H-bonding network that includes a water molecule and the side chains of N52, T78, and the axial ligand M80. − ,, These interactions are regarded as important determinants of the redox potential and ET reorganization energy of cyt c . ,,− Moreover, Y67 is considered crucial in tertiary structure stabilization as it participates in H-bonds that interconnect loops 40–57 and 71–85, which are involved in pH-dependent and other conformational changes relevant to the apoptotic function. ,,− F82 is a conserved surface residue located in the region of interaction with partner redox proteins but also in close proximity to the heme and, therefore, has been implicated in modulating the redox potential and in establishing efficient interprotein ET pathways. ,, The highly conserved prolines 30, 71, and 76 are thought to play important structural roles. P30 is important in stabilizing the distal H18 ligand; P71 helps to position the proximal ligand M80 and contributes to shield the heme group from the bulk solvent. − T78, also a conserved residue, participates in a H-bonding network that is important for determining the heme environment . Finally, the remaining highly conserved residue K72 is part of the patch of positively charged residues in cyts c from higher organisms that surround the partially exposed heme and participate in electrostatic interactions with the partner redox proteins, as well as with natural and artificial membranes , and with Apaf-I. , Interestingly, in yeast iso-1-cyt c , the K72 residue is naturally trimethylated, which along with the presence of free C102 constitutes a distinct feature .…”

Characterization of Intramolecular Interactions of Cytochrome c Using Hydrogen–Deuterium Exchange-Trapped Ion Mobility Spectrometry–Mass Spectrometry and Molecular Dynamics

“…It has been reported that Trp59 and Met80 residues provide a unique hydrophobic environment to the heme crevice. 77,78 Without these interactions, the crevice opens up, exposing Thr78 and Pro71, which are residues involved in the formation and stabilization of the heme crevice due a network of hydrogen bonds around the heme group. 79 The interface formed by the interaction of the helices occurs immediately after the covalent binding of the heme group to the polypeptide via thioether bonds.…”

“…For example, inspection of the candidate structures revealed that major structural differences are associated with the increase in distance between the N- and C- terminal helices and the solvent exposure of the heme cavity at higher charge states are consistent with previous results. − That is, the +10 charge state structures are characterized by the destabilization of the secondary structure of the N- and C- terminal helices and cleavage of the Trp59 and of the Met80 residues and the heme propionate hydrogen bond. It has been reported that Trp59 and Met80 residues provide a unique hydrophobic environment to the heme crevice. , Without these interactions, the crevice opens up, exposing Thr78 and Pro71, which are residues involved in the formation and stabilization of the heme crevice due a network of hydrogen bonds around the heme group . The interface formed by the interaction of the helices occurs immediately after the covalent binding of the heme group to the polypeptide via thioether bonds .…”

Axial ligand modified high valent tin(iv) porphyrins: synthesis, structure, photophysical studies and photodynamic antimicrobial activities on Candida albicans

“…The organism was grown aerobically at 37 C in a standard YPD medium containing 1% yeast extract, 2% peptone, and 2% dextrose. 18 Since the strain is ura À , the growth medium was supplemented with 25 mg mL À1 uridine. 19 Agar well diffusion assay for determining the photodynamic growth inhibition of C. albicans YPD broth and YPD agar supplemented with uridine were prepared and sterilized by autoclaving.…”