Send to

Choose Destination
See comment in PubMed Commons below
J Pharm Sci. 2011 May;100(5):1679-89. doi: 10.1002/jps.22426. Epub 2011 Jan 12.

Mechanisms of m-cresol-induced protein aggregation studied using a model protein cytochrome c.

Author information

Department of Pharmaceutical Sciences and Center for Pharmaceutical Biotechnology, School of Pharmacy, University of Colorado Denver, 12700 E 19th Ave., C238-P15, Aurora, Colorado 80045, USA.


Multidose protein formulations require an effective antimicrobial preservative (AP) to inhibit microbial growth during long-term storage of unused formulations. m-cresol (CR) is one such AP, but it has been shown to cause protein aggregation. However, the fundamental physical mechanisms underlying such AP-induced protein aggregation are not understood. In this study, we used a model protein cytochrome c to identify the protein unfolding that triggers protein aggregation. CR induced cytochrome c aggregation at preservative concentrations that are commonly used to inhibit microbial growth. Addition of CR decreased the temperature at which the protein aggregated and increased the aggregation rate. However, CR did not perturb the tertiary or secondary structure of cytochrome c. Instead, it populated an "invisible" partially unfolded intermediate where a local protein region around the methionine residue at position 80 was unfolded. Stabilizing the Met80 region drastically decreased the protein aggregation, which conclusively shows that this local protein region acts as an aggregation "hotspot." On the basis of these results, we propose that APs induce protein aggregation by partial rather than global unfolding. Because of the availability of site-specific probes to monitor different levels of protein unfolding, cytochrome c provided a unique advantage in characterizing the partial protein unfolding that triggers protein aggregation.

[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Support Center