R 1325 (OTTO) D-Ribose, 99% Cas 50-69-1 - used as a substrate in determination of pentokinase. R 1325 (OTTO) D-Ribose, 99% Cas 50-69-1 - used as a building block for a lot of the signals and products throughout the metabolic pathway. One of the most important products of the metabolic pathway is adenosine triphosphate (ATP), which provides energy that drives processes in cells.