Pengembangan peptida inhibitor alfa-glukosidase dari hidrolisat kasein susu kambing (Capra hircus) melalui pendekatan in-silico digestion dengan tripsin dan penambatan molekul

Kiranti Aulia, Prof. Dr. Tri Joko Raharjo, M.Si., Ph.D., Dr. Endang Astuti, M.Si.

2025 | Tesis | S2 Ilmu Kimia

Peptida bioaktif dari hidrolisis kasein susu kambing berpotensi sebagai obat dalam beberapa penyakit, salah satunya adalah penyakit Diabetes melitus, dengan menginhibisi alfa-glukosidase. Penelitian ini bertujuan mengidentifikasi urutan asam amino peptida bioaktif inhibitor alfa-glukosidase dari hidrolisat kasein susu kambing secara in silico, kemudian mengoptimasi struktur peptida untuk meningkatkan aktivitas penghambatannya terhadap enzim alfa-glukosidase.

Kasein susu kambing dihidrolisis melalui in silico digestion melalui server Expasy PeptideMass dengan tripsin. Peptida yang dihasilkan diidentifikasi bioaktivitasnya dengan server dan penambatan molekul digital seperti PeptideRanker, Pepsite2, dan HADDOCK guna mengkaji interaksinya dengan alfa-glukosidase. Peptida terpilih disintesis dan diuji aktvitas penghambatannya terhadap alfa-glukosidase untuk memperoleh nilai IC50. Peptida menunjukkan aktivitas penghambatan, kemudian dioptimasi dan dimodifikasi secara in silico hingga mendapatkan peptida termodifikasi dengan interaksi dan aktivitas yang paling potensial. Selanjutnya peptida termodifikasi disintesis, diuji aktivitas penghambatannya, ditentukan nilai IC50, serta tipe penghambatannya secara in vitro. 

Berdasarkan analisis secara in silico dan penambatan molekul diperoleh peptida yang paling berpotensi sebagai inhibitor alfa-glukosidase adalah “EMPFPK” dengan interaksi yang kuat dan stabil terhadap ?-glukosidase. Hasil uji aktivitas secara in vitro menunjukkan peptida “EMPFPK” berpotensi menginhibisi alfa-glukosidase dengan nilai IC50 sebesar 313,420±1,613 µM. Modifikasi pada peptida “EMPFPK” berhasil dilakukan, peptida termodifikasi “RMPFPR” menunjukkan peningkatan aktivitas penghambatan alfa-glukosidase yang ditunjukkan dengan interaksi yang lebih kuat dan stabil terhadap triad katalitik Asp215 dan Asp352, serta penurunan nilai IC50 menjadi 140,792±1,827 µM dengan tipe penghambatan campuran.

Bioactive peptides derived from the hydrolysis of goat milk casein have potential as therapeutic agents for various diseases, including diabetes mellitus, by inhibiting alpha-glucosidase. This study aimed to identify the amino acid sequences of alpha-glucosidase–inhibitory bioactive peptides from goat milk casein hydrolysates in silico, and to optimize peptide structures to enhance their inhibitory activity against alpha-glucosidase.

Goat milk casein was hydrolyzed in silico using the Expasy PeptideMass server with trypsin. The resulting peptides were evaluated for bioactivity using digital screening and molecular docking tools such as PeptideRanker, Pepsite2, and HADDOCK to examine their interactions with alpha-glucosidase. Selected peptides were synthesized and tested for alpha-glucosidase inhibitory activity to determine their IC?? values. Peptides showing inhibitory activity were subsequently optimized and modified in silico to obtain derivatives with the strongest predicted interactions and inhibitory potential. The modified peptides were then synthesized, their inhibitory activities were assessed, IC?? values were determined, and their inhibition types were characterized in vitro.

Based on in silico analysis and molecular docking, the peptide “EMPFPK” exhibited the strongest and most stable interaction with alpha-glucosidase and was identified as the most promising inhibitor. In vitro activity assays showed that “EMPFPK” inhibited alpha-glucosidase with an IC?? value of 313.420 ± 1.613 µM. Structural modification of “EMPFPK” yielded the derivative “RMPFPR” which demonstrated enhanced alpha-glucosidase inhibitory activity, evidenced by stronger and more stable interactions with the catalytic triad residues Asp215 and Asp352, and reduced IC?? value of 140.792 ± 1,827 µM with a mixed-type inhibition.

Kata Kunci : Diabetes melitus, alfa-glukosidase, peptida, penambatan molekul