A structural role for arginine in proteins: Multiple hydrogen bonds to backbone carbonyl oxygens

We propose that arginine side chains often play a previously unappreciated general structural role in the maintenance of tertiary structure in proteins, wherein the positively charged guanidinium group forms multiple hydrogen bonds to backbone carbonyl oxygens. Using as a criterion for a “structural” arginine one that forms 4 or more hydrogen bonds to 3 or more backbone carbonyl oxygens, we have used molecular graphics to locate arginines of interest in 4 proteins: Arg 180 in Thermus thermophilus manganese superoxide dismutase, Arg 254 in human carbonic anhydrase II, Arg 31 in Streptomyces rubiginosus xylose isomerase, and Arg 313 in Rhodospirillum rubrum ribulose‐1,5‐bisphosphate carboxylase/oxygenase. Arg 180 helps to mold the active site channel of superoxide dismutase, whereas in each of the other enzymes the structural arginine is buried in the “mantle” (i.e., inside, but near the surface) of the protein interior well removed from the active site, where it makes 5 hydrogen bonds to 4 backbone carbonyl oxygens. Using a more relaxed criterion of 3 or more hydrogen bonds to 2 or more backbone carbonyl oxygens, arginines that play a potentially important structural role were found in yeast enolase, Bacillus stearothermophilus glyceraldehyde‐3‐phosphate dehydrogenase, bacteriophage T4 and human lysozymes, Enteromorpha prolifera plastocyanin, HIV‐1 protease, Trypanosoma brucei brucei and yeast triosephosphate isomerases, and Escherichia coli trp aporepressor (but not trp repressor or the trp repressor/operator complex). In addition to helping form the active site funnel in superoxide dismutase, the structural arginines found in this study play such diverse roles as stapling together 3 strands of backbone from different regions of the primary sequence, and tying α‐helix to α‐helix, βturn to β‐turn, and subunit to subunit. Copyright © 1994 The Protein Societ

Beliefs and attitudes regarding drug treatment: Application of the Theory of Planned Behavior in African-American cocaine users

The Theory of Planned Behavior (TPB) can provide insights into perceived need for cocaine treatment among African American cocaine users

The Criminal Justice Experience of African American Cocaine Users in Arkansas

BackgroundAfrican Americans are incarcerated at rates much higher than other racial and ethnic groups in the United States.ObjectivesWe sought to qualitatively explore the relationships between ongoing involvement in the criminal justice system and continued drug use in a population of urban and rural African American cocaine users in a southern state.MethodsSemi-structured qualitative interviews were conducted among African American cocaine users in Arkansas between 2010 and 2012. Participants resided in both rural (two counties located in the eastern Arkansas Mississippi delta region) and urban (the county including the capital city of Little Rock) areas.ResultsNumerous important themes emerged from participants' narratives, including chronic involvement with the criminal justice system (being a "career criminal"), continued access to drugs while incarcerated, relapse, and reincarceration and lack of access to effective drug treatment. Conclusion/Importance: The themes which emerged from our data speak to the collective experience that many substance using populations in the United States face in dealing with the criminal justice system. Our findings highlight the need to better, more holistic ways of engaging African American substance users in community based substance use treatment and supportive services

The Role of Social Capital in African Americans' Attempts to Reduce and Quit Cocaine Use.

BackgroundResearch examining substance users' recovery has focused on individual-level outcomes while paying limited attention to the contexts within which individuals are embedded, and the social processes involved in recovery.ObjectivesThis paper examines factors underlying African American cocaine users' decisions to reduce or quit cocaine use and uses practice theory to understand how lifestyle changes and shifts in social networks facilitate access to the capital needed to change cocaine use patterns.MethodsThe study, an in-depth analysis of substance-use life history interviews carried out from 2010 to 2012, included 51 currently not-in-treatment African American cocaine users in the Arkansas Mississippi Delta region. A blended inductive and deductive approach to data analysis was used to examine the socio-cultural and economic processes shaping cocaine use and recovery.ResultsThe majority of participants reported at least one lifetime attempt to reduce or quit cocaine use; motivations to reduce use or quit included desires to meet social role expectations, being tired of using, and incarceration. Abstinence-supporting networks, participation in conventional activities, and religious and spiritual practices afforded access to capital, facilitating cocaine use reduction and sobriety.ConclusionsInterventions designed to increase connection to and support from nondrug using family and friends with access to recovery capital (e.g., employment, faith community, and education) might be ideal methods to reduce substance use among minorities in low-income, resource-poor communities

The Role of Social Capital in African Americans' Attempts to Reduce and Quit Cocaine Use.

BackgroundResearch examining substance users' recovery has focused on individual-level outcomes while paying limited attention to the contexts within which individuals are embedded, and the social processes involved in recovery.ObjectivesThis paper examines factors underlying African American cocaine users' decisions to reduce or quit cocaine use and uses practice theory to understand how lifestyle changes and shifts in social networks facilitate access to the capital needed to change cocaine use patterns.MethodsThe study, an in-depth analysis of substance-use life history interviews carried out from 2010 to 2012, included 51 currently not-in-treatment African American cocaine users in the Arkansas Mississippi Delta region. A blended inductive and deductive approach to data analysis was used to examine the socio-cultural and economic processes shaping cocaine use and recovery.ResultsThe majority of participants reported at least one lifetime attempt to reduce or quit cocaine use; motivations to reduce use or quit included desires to meet social role expectations, being tired of using, and incarceration. Abstinence-supporting networks, participation in conventional activities, and religious and spiritual practices afforded access to capital, facilitating cocaine use reduction and sobriety.ConclusionsInterventions designed to increase connection to and support from nondrug using family and friends with access to recovery capital (e.g., employment, faith community, and education) might be ideal methods to reduce substance use among minorities in low-income, resource-poor communities