Improvement of ACE inhibitory activity of chitooligosaccharides (COS) by carboxyl modification Original Research Article

In the present research, chitooligosaccharides (COS) were carboxylated with –COCH2CH2COO− groups to obtain specific structural features similar to Captopril®. Angiotensin I converting enzyme (ACE) inhibitory activity of carboxylated COS was studied and observed to enhance its activity with increased substitution degree. Further, Lineweaver–Burk plot analysis revealed that inhibition was competitive via obligatory binding site of the enzyme. This was accompanied with substitution of positively charged quarternized amino groups to COS with different substitution degrees, in which negative impact on ACE inhibition was observed.