$CDP-6-Deoxy-{Delta}^{3,4}-glucoseen$ Reductase(E3)는 iodoactic acid나 DTNB에 의하여 활성도를 저해시킬 수 있었고, MADH를 사용하여 환원시킴에 따라 DTNB에 의하여 적정되는 thiol의 갯수가 증가하였다. 여러 가지 산화상태에 있는 E3의 thiol을 DTNB로 적당한 결과로 볼때, 최소한 하나의 환원 가능한 disulfide가 E3의 active-site 근처에 존재함을 알 수가 있었다. 또한 E3가 과량의 NADH에 의하여 inactivation되는 것을 관찰하였으며 이러한 결과들은 완전히 환원된 상태의 E3는 활성이 없지만 redox-active disulfide가 E3의 반응기작에 참여하는 것을 시사하고 있다. ${Delta}^{3,4}-glucoseen$ 중간체와 같은 conjugated imine이 thiol에 의하여 환원되는 계의 화학적 모델로서 cysteine에 의한 DCPIP의 환원반응 속도를 고찰하였다.
The NADH oxidase activity of $CDP-6-Deoxy-{Delta}^{3,4}-glucoseen$ Reductase(E3) was decreased by thiol modifying agents such as iodoacetic acid or DTNB. The enzyme was reduced by NADH and the number of free thiols was gradually increased by the reduction. The titration of free thiols in E3 at various redox-stages by DTNB revealed that the enzyme contained at least one reducible disulfide near the active-site. This result, together with studies on the inactivation of E3 by excess NADH, indicates the redox-active disulfide may be involved in the catalytic cycle of E3 although the fully reduced form of the enzyme is catalytically inactive. In an attempt to establish a chemical model for the reduction of the conjugated imine such as ${Delta}^{3,4}-glucoseen$ intermediate by thiols, kinetics of the reduction of DCPIP by cysteine was examined.
