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.
CRUK and EPSRC Cancer Imaging Centre, Institute of Cancer Research, Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK.
Yann
Y
Jamin
Cristina
C
Gabellieri
Lynette
L
Smyth
Steven
S
Reynolds
Simon P
SP
Robinson
Caroline J
CJ
Springer
Martin O
MO
Leach
Geoffrey S
GS
Payne
Thomas R
TR
Eykyn
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