Hyperpolarized (13)C magnetic resonance detection of carboxypeptidase G2 activity.
Carboxypeptidase G2 (CPG2) is a bacterial enzyme that is currently employed in a range of targeted cancer chemotherapy strategies such as gene-directed enzyme prodrug therapy (GDEPT). Employing dynamic nuclear polarization (DNP) and natural abundance (13)C magnetic resonance spectroscopy (MRS), we observed the CPG2-mediated conversion of a novel hyperpolarized reporter probe 3,5-difluorobenzoyl-L-glutamic acid (3,5-DFBGlu) to 3,5-difluorobenzoic acid (3,5-DFBA) and L-glutamic acid (L-Glu) in vitro. Isotopic labeling of the relevant nuclei with (13)C in 3,5-DFBGlu or related substrates will yield a further factor of 100 increase in the signal-to-noise. We discuss the feasibility of translating these experiments to generate metabolic images of CPG2 activity in vivo.
Jamin
Yann
Y
CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research, Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
Gabellieri
Cristina
C
Smyth
Lynette
L
Reynolds
Steven
S
Robinson
Simon P
SP
Springer
Caroline J
CJ
Leach
Martin O
MO
Payne
Geoffrey S
GS
Eykyn
Thomas R
TR
D000465:Algorithms; D002247:Carbon Isotopes / Q000032:analysis / Q000737:chemistry; D004789:Enzyme Activation; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011623:gamma-Glutamyl Hydrolase / Q000032:analysis* / Q000737:chemistry*
D002247:Carbon Isotopes; D011623:gamma-Glutamyl Hydrolase