I am not sure if I mentioned before, but one of my favorite journals is Journal of Biological Chemistry. The journal has these "Classics" series where you can read really nice reviews, biographies about scientists and important scientific discoveries.
So, this one is a short introduction for Prof. Rajagopalan and his discovery of molybdopterin. You can go for the references for the details of his discoveries and research.
It is a free article that you can read here: