Judul: Antibacterial Activity from Enzymatic Hydrolysis of Goat’s Milk Whey.
Abstrak: Penggunaan bahan tambahan pangan berupa bahan kimia untuk mencegah dan menghambat pertumbuhan mikoorganisme dan memperpanjang umur simpan memiliki dampak lain terhadap keamanan penggunaanya terutama munculnya resistensi mikroorganisme terhadap antimikroba sintetik. Hal ini mendorong pengembangan antimikroba yang berasal dari bahan alami salah satunya yang berasal dari bahan pangan hewani yaitu susu. Komponen bioaktif protein susu tidak selalu ada dalam keadaan alamiahnya diantaranya dapat berupa prekursor atau peptida yang hanya akan aktif apabila telah dihidrolisis secara in vitro dari protein alamiahnya. Hidrolisis terhadap protein susu dapat dilakukan menggunakan enzimenzim proteolitik dari berbagai sumber, diantaranya adalah enzim yang berasal dari Bacillus lincheniformis. Penelitian ini menggunakan konsentrasi enzim Bacillus lincheniformis yang berbeda (0,5%, 1% dan 1,5%) untuk menghasilkan hirdolisat yang memiliki aktivitas antibakteri dilihat dari nilai kadar protein, profil SDS PAGE dan besarnya zona hambat (metode cakram). Proses hidrolisis menghasilkan kadar protein sebesar 0,027-0,049 mg/mL dengan aktivitas antibakteri sebesar 8,8 mm untuk Escherichia coli pada whey yang dihidrolisis dengan enzim taraf 1,5 %dan 8,7mm untuk Staphylococcus aureus pada whey yang dihidrolisis dengan enzim taraf 1 %. Hasil dari hidrolisis juga menghasilkan peptida dengan berat molekul < 5 kDa., Food additives had been used to prevent and inhibit the growth of microorganisms and extend shelf life of food. Based on the safety of their used, it has an impact such as microorganism resistance to synthetic antimicrobials. This encourages the development of antimicrobials derived from natural ingredients, especially from milk. The bioactive components of milk protein have not always existed in their natural state, including precursors or peptidas that will only be active if they have been hydrolyzed in vitro from their natural proteins. Hydrolysis of milk protein can be carried out using proteolytic enzymes from various sources, including enzymes from Bacillus lincheniformis. This study used in different concentrations of the enzyme Bacillus lincheniformis (0.5%, 1% and 1.5%) to produce hydrolyzate which has antibacterial activity in terms of protein content, SDS PAGE profile and the size of the inhibition zone (disc method). The hydrolysis process resulted in a protein content of 0.027- 0.049 mg/mL with an antibacterial activity of 8.8mm in Escherichia coli in whey hydrolyzed with enzyme level 1.5% and 8.7 mm for Staphylococcus aureus in whey hydrolyzed with enzyme level 1 %. The result of hydrolysis also produces protein with a molecular weight of < 5 kDa.
Keyword: antibakteri, protease Bacillus lincheniformis, hidrolisis, susu kambing

Judul: Protease Enzyme DPP4 Inhibitor Activity of Peptide from Hydrolyzed Etawa Crossbreed Goat Milk
Abstrak: Susu kambing merupakan sumber protein sebanding dengan susu sapi dengan kadar protein yang mencapai 4,71% sedangkan susu sapi pada kisaran 3,4%. Susu kambing lebih mudah dicerna karena ukuran misel kasein yang lebih kecil. Susu kambing yang dihidrolisis menghasilkan peptida dengan sifat bioaktif. Peptida bioaktif protein susu kambing memiliki manfaat bagi kesehatan tubuh seperti antihipertensi, antioksidan, dan antidiabetes. Sifat bioaktif antidiabetes susu kambing dapat bekerja melalui mekanisme inhibisi enzim dipeptidil peptidase 4 (DPP4). Penelitian bertujuan untuk mengetahui pengaruh hidrolisis terhadap kadar protein, aktivitas inhibisi DPP4, dan profil peptida susu kambing peranakan etawa. Susu kambing yang telah dipisahkan lemaknya dihidrolisis menggunakan enzim papain dengan aktivitas enzim spesifik 1,48 ± 0,04 U/mg pada suhu 37ºC pH 7,0. Variasi waktu hidrolisis yang digunakan adalah 0(non-hidrolisis), 1, 4, dan 24 jam. Kadar protein susu kambing mengalami penurunan dengan adanya perlakuan hidrolisis, dengan kadar protein sampel berturut sebesar 8,16; 6,74; 6,43; dan 5,96 mg/mL. Analisis aktivitas inhibisi DPP4 menunjukkan peningkatan dengan perlakuan hidrolisis, dengan aktivitas inhibisi terendah pada sampel non-hidrolisis sebesar 16,81 ± 13,83% dan aktivitas tertinggi pada hidrolisat 24 jam sebesar 96,05 ± 1,49%. Analisis profil protein menggunakan SDS-PAGE menunjukkan bahwa hidrolisis memotong protein dengan berat molekul besar seperti laktoferin (87kDa) dan Kasein (25 – 44kDa), menyisakan protein berat molekul rendah diantaranya adalah β-laktoglobulin (16 kDa) dan α-laktalbumin (10kDa)., Goat's milk is a comparable protein source to cow's milk with protein contents reaching 4,71% while cow's milk at around 3,4%. Goat milk is easier to digest due to the smaller size of casein micelles. Hydrolyzed goat milk contains peptides with bioactive properties. Bioactive peptides of goat milk protein have health benefits such as antihypertensive, antioxidant, and antidiabetic. The antidiabetic bioactive properties of goat milk can work through aimed at dipeptidyl peptidase 4 (DPP4) enzyme inhibition. This study aims to determine the effect of hydrolysis on protein content, DPP4 inhibition activity, and peptide profile of etawa crossbreed goat milk. Fat separated goat milk was hydrolyzed using papain enzyme with specific enzyme activity of 1,48 ± 0,04 U/mg at 37ºC pH 7,0. The hydrolysis time variations used were 0 (non-hydrolyzed), 1, 4, and 24 hours. Goat milk protein levels decreased with hydrolysis treatment, with protein levels of samples at 8,16; 6,74; 6,43; and 5,96 mg/mL consecutively. Analysis of DPP4 inhibition activity showed an increase with hydrolysis treatment, with the lowest inhibition activity in the non-hydrolyzed sample at 16.81 ± 13.83% and the highest activity in the 24-hour hydrolysate at 96,05 ± 1.49%. Protein profile analysis using SDS-PAGE showed that hydrolysis cut large molecular weight proteins such as lactoferrin (87kDa) and casein (25 - 44kDa), leaving low molecular weight proteins such as β-lactoglobulin (16 kDa) and α-lactalbumin (10kDa).
Keyword: antidiabetic, bioactive peptide, goat milk, papain, SDS-PAGE

Judul: Tree berdiameter lima adalah graceful
Abstrak: This manuscript presents some proofs that every tree of diameter five is graceful. A graceful tree is a graph which has a graceful labelling. This labelling assigns absolute difference of connected vertices, such that the resulting edge labels are mutually distinct. There are three theorems to be considered. First theorem proves that every tree of diameter four is graceful. Second theorem proves that every tree of diameter five is graceful or nearly graceful. The third theorem improves the second theorem and shows that every tree of diameter five is nearly graceful, which can be transformed into graceful using some certain patterns.
Keyword: Graf, Pelabelan graceful, Bogor Agricultural University, Institut Pertanian Bogor, IPB