Many organelle enzymes coded for by nuclear genes have N-terminal sequences, which directs them into the organelle (precursor) and are removed upon import (mature). The experiments described below charac-terize the differences between the precursor and mature forms of water-melon glyoxysomal malate dehydrogenase. Using recombinant protein methods, the precursor (p-gMDH) and mature (gMDH) forms were puri-fied to homogeneity using Ni 2+ –NTA affinity chromatography. Gel filtra-tion and dynamic light scattering have shown both gMDH and p-gMDH to be dimers in solution with p-gMDH having a correspondingly higher molecular weight. .
