those of YFF. This indicates that C

those of YFF. This indicates that COS molecules have really linked
onto the enzyme molecules after chemical modification and that
the YFF modification with COS has been successfully achieved.
3.5. Changes of sugar contents and amino modification ratio after
modification
After modification with COS, chitooligosaccharide chains were
linked to the amino groups of saccharide chains of YFF, which
enhanced the saccharification extent of enzyme. The sugar content
was increased from 56% (1.25 mg/mg Pro) to 71.5% (2.51 mg/mg
Pro) after modification. The amino modification ratio was 49.4%
(Table 5). According to the results, it could be deduced that the chitooligosaccharide molecules might be firstly split to short chains in
activating process. The short chains of chitooligosaccharides were
then linked to the amino groups of saccharide chains of YFF.
3.6. Changes in the enzymatic properties after modification
3.6.1. The optimum pH and pH stability of YFF and COSFF
As shown in Fig. 3, the optimum pH of COSFF shifted from pH5.0
for YFF to pH 4.5. The results in Fig. 4 indicated that the stability of
modified enzyme in acidic condition was higher than that of natural
enzyme. After incubation at pH 4.0 and 50
◦
C for 2 h, the modified
enzyme (COSFF) retained about 98% of its original activity whereas
the natural enzyme (YFF) retained only about 59.8% as comparison. In pH 7.0, the stability of modified enzyme slightly dropped.
After incubation for 10 min in pH 7.0, the activities of modified and
natural enzymes dropped rapidly.
3.6.2. The optimum temperature and thermostability of YFF and
COSFF
The optimum temperature showed no significant change after
modification. The optimum temperature of YFF was 50–55
◦
C and

Hasil (Bahasa Indonesia) 1:

mereka YFF. Ini menunjukkan bahwa COS molekul telah benar-benar terhubungke molekul enzim setelah kimia modifikasi dan bahwaYFF modifikasi dengan COS telah berhasil dicapai.3.5. perubahan isi gula dan modifikasi amino rasio setelahModifikasiSetelah modifikasi dengan COS, rantai chitooligosaccharide yangterkait dengan kelompok amino rantai sakarida YFF, yangmeningkatkan tingkat enzim saccharification. Kadar gulameningkat dari 56% (1,25 mg/mg Pro) 71.5% (2.51 mg/mgPro) setelah modifikasi. Rasio amino modifikasi adalah 49.4%(Tabel 5). Menurut hasil, itu dapat disimpulkan bahwa molekul chitooligosaccharide mungkin pertama dibagi ke rantai pendek dimengaktifkan proses. Rantai pendek chitooligosaccharides yangkemudian terkait dengan kelompok amino rantai sakarida YFF.3.6. perubahan dalam sifat-sifat enzim setelah modifikasi3.6.1. pH optimal dan stabilitas pH YFF dan COSFFSeperti ditunjukkan dalam gambar 3, pH optimal COSFF bergeser dari pH5.0untuk YFF untuk pH 4,5. Hasil dalam gambar 4 menunjukkan bahwa stabilitasdiubah enzim dalam kondisi asam adalah lebih tinggi dari alamenzim. Setelah inkubasi pada pH 4.0 dan 50◦C untuk 2 h, diubahenzim (COSFF) disimpan sekitar 98% dari aktivitas asli sedangkanenzim alami (YFF) dipertahankan hanya sekitar 59,8% sebagai perbandingan. PH 7.0, stabilitas enzim dimodifikasi sedikit turun.Setelah inkubasi untuk 10 min pH 7.0, kegiatan dimodifikasi danenzim alami turun dengan cepat.3.6.2. suhu optimum dan thermostability YFF danCOSFFSuhu optimum yang menunjukkan tidak ada perubahan signifikan setelahmodifikasi. Suhu optimal YFF adalah 50-55◦C dan