Background and Aim: Angiotensin-converting enzyme (ACE) is one of the inhibitory enzymes isolated from animals for the treatment of hypertension. ACE inhibitor (ACE-I) peptides can be obtained by hydrolyzing proteins from various animal tissues, including muscle and connective tissues. However, the study on ACE-I activity from collagen of Kacang goat skin has not been conducted. This study explores the potency of collagen from Kacang goat skin as a source of an antihypertensive agent through ACE inhibition. Thermolysin will hydrolyze collagen and produce the peptide classified antihypertensive bioactive peptides. This study aimed to determine the potential of thermolysin to hydrolyze collagen of Kacang goat skin for ACE-I peptide production and to identify the production of ACE-I peptides.

Materials and Methods: Collagen from Kacang goat skin was hydrolyzed with thermolysin and incubated at 37°C for 1 h. Molecular weight (MW) evaluation was performed by SDS PAGE; fractionation peptides at <5 kDa, 3-5 kDa, and <3 kDa were performed by ultrafiltration and ACE-I activity determined by IC₅₀ measurement.

Results: Collagen was hydrolyzed by thermolysin, resulting in protein with MW of 117.50-14.60 kDa. The protein content of fractionation at >5 kDa was 3.93±0.72 mg/mL, content of 3-5 kDa was 3.81±0.68 mg/mL, and that of <3 kDa was 2.33±0.38 mg/mL. Fractionation was performed 3 times and one of the results was selected for the ACE-I test. The selected fraction was tested by IC₅₀ measurement with three repetitions and it showed an average enzyme activity at 0.83 μg/mL or 82.94 mg/mL.

Conclusion: Thermolysin hydrolysis of collagen from Kacang goat skin showed the potential to produce bioactive peptides, such as ACE-I.

Keywords: angiotensin-I-converting enzyme inhibitor, bioactive peptides, collagen, hydrolysis, thermolysin.