136429-81-7 Oxytocin, 1-(3-mercapto-L-valine)-2-D-phenylalanine-4-L-threonine-8-L-ornithine- Oxytocin, pen(1)-phe(2)-thr(4)-orn(8)- Oxytocin, penicillamine(1)-phenylalanyl(2)-threonyl(4)-ornithine(8)- PPTOO Pen(1)-phe(2)-thr(4)-orn(8)-oxytocin