An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Thermodynamic Measurements for Inactivation of Bioterrorism Agents Ricin and Abrin

Investigators
Tolleson, William
Institutions
DHHS/FDA - National Center for Toxicological Research
Objective
1. Measure forward-rate constants for thermal denaturation of ricin and abrin at seven temperatures (60, 65, 70, 75, 80, 85, 90, and 95 C) and three buffer combinations (0.10 M NaCl buffered with 20 mM lactate, pH 3.0; 20 mM acetate, pH 5.0; and 20 mM phosphate, pH 7.0) by monitoring the quenching of intrinsic protein (tryptophan) fluorescence (EX295, EM340) in a thermostatted spectrofluorimeter.

2. Exploit results (Tm, Delta H) gathered using differential-scanning calorimetry at NCFST to select Tm for toxin proteins and measure reverse-rate constants (protein renaturation) at one temperature and one buffer combination. Calculate Keq and Delta G from ratio of rates. Determine T Delta S from Delta G and Delta H.

3. Determine the influence of solvent pH on isothermal toxin folding/unfolding equilibria.

4. Identify time-, pH-, and temperature-dependent reversible and irreversible transitions in ricin conformation and correlate these with changes in toxi-dependent enzyme activity and cytotoxicity.

More information
Responsible Division: Biochemical Toxicology
Collaborating FDA Center(s): CFSAN
Funding Source
Nat'l. Center For Toxicological Research
Project number
P00708
Categories
Food Defense and Integrity
Natural Toxins