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Cyclic voltammetry (CV), UV−visible (UV−vis), circular dichroism (CD), and resonance Raman (λex = 406.7, 413.1 nm) spectroscopy have been used to probe the structure and redox function of horse cytochrome c (cyt c) in aqueous mixtures of three water-miscible organic solvents, specifically, acetonitrile (ACN), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) containing 100−60% water. As the concentration of the organic solvent is increased, significant changes are observed in the spectroscopy of ferricytochrome c (ferricyt c) with the greatest structural changes observed for ferricyt c in mixed solvent media with the lowest dielectric constant (30% ACN in this work). In the UV−visible spectrum, the Soret band blue shifts (1 nm) and the intensity of the 695 nm band decreases. UV CD (185−240 nm) suggest that changes in the protein secondary structure on going from aqueous to nonaqueous media are relatively small and that the protein structure remains largely intact in nonaqueous media. In the visible CD spectrum, the negative 417 nm CD signal disappears, signaling significant changes in heme−polypeptide interactions. Shifts in the vibrational frequencies and changes in the relative intensities of bands in both the marker band and low frequency spectral regions of cyt c in mixed media have been attributed to mixtures of the type IVa, IVb, Va, and Vb alkaline conformers of ferricyt c in mixed media. The change in the composition of these mixtures as the dielectric constant decreases parallels closely that reported by Dopner et al. for yeast iso-1-cytochrome c in aqueous solution as the aqueous solution pH is raised from pH 7 to pH 10. The spectroscopic characteristics of the reduced form of cyt c in mixed solvents are very similar to those of native ferrous cyt c (ferrocyt c) in aqueous solution, reflecting minimal change in heme active site structure in the reduced state. Cyt c in mixed solvents exhibits a quasireversible, one-electron response at 4,4‘-dipyridyl disulfide-modified Au electrodes between 5 and 200 mV/s. The redox potential for cyt c in mixed media (199−274 mV vs SHE) and the rate of heterogeneous electron transfer (0.4−3.5 × 10-3 cm/s) decrease as the organic solvent content of the solvent medium increases. Our data support the conclusion that the internal dielectric constant within the heme crevice plays the key role in determining the reduction potential of cyt c and suggest that the effects of axial ligation (Met vs Lys) may be less significant than previously believed.

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This article summarizes the findings of a survey study of undergraduate research (UR) students presenting their research at the fall 2007 and fall 2008 American Chemical Society (ACS) National Meetings. The purpose of the study is to probe the perceived benefits of conference participation to UR students. Results suggest that participation in professional meetings such as the ACS National Meeting is a vital element of the UR experience and an important factor in the enculturation of student scientists into the greater scientific community. Participation provides student researchers an opportunity to communicate their UR findings to the greater scientific community and strengthens their commitment to the pursuit of a career in chemistry and advanced study. Gender does not appear to influence student views concerning meetings nor student selection of meeting activities. However, ethnicity does appear to influence student views and student selection of meeting activities. Meeting participation appears to provide a forum for African-American students where they feel they can test and affirm their professional self-identity and hone their presentation skills. These findings suggest that participation in technical conferences is an important element in the enculturation of student researchers in the greater scientific community and that meeting participation may be particularly important in the enculturation of African-American student scientists. Student respondents participated in a wide range of activities at the ACS National Meetings, both formal and informal. However, for the most part they elected to participate in the technical activities, specifically, the poster sessions, the exposition, and the undergraduate programming. Comparison of students' stated motivations for attending the ACS National Meeting and their actual selection of meeting activities suggests that students may not be aware of some of the meeting activities nor of the benefits of participating in these activities as they relate to the students' stated meeting goals. Thus, it may be valuable to develop instructional materials and exercises to educate students concerning technical conferences. Finally, UR students attending graduate research universities do not appear to enjoy the same opportunities for participation in professional conferences that their peers attending primarily undergraduate institutions and comprehensive universities do. Since evidence of research experience and productivity are commonly used criteria for offers of graduate school admission and financial aid, this observation merits further study.