... evidence of polar environment around ArgB263.It consists of O atoms of the main chain CO groups of LeuB387 and TrpB240, Od1atom of AsnB241 and Oc atom of SerB386 and is expected to stabilize the ... F., van Langen, L.M., Wegman,M .A. , Cao, L. & Janssen, M.H .A. (2001) Biocatalysis and biocatalyst in the synthesis of b-lactam antibiotics. In: Synthesis of b-Lactam Antibiotics. Chemistry, ... PhAc-pAB, PhAc-mAB,PhAc-oAB vs. phenylacetyl 4-nitroanilide (PhAc-pNA),NIPAB and iso-NIPAB, but it suggests an explanation of the 16-fold difference between the Kmvalues of PhAc-MCA and PhAc-bNA...