%A 1117011005 APRILIA ISMA DENILA  
%T PENGARUH PENAMBAHAN SORBITOL TERHADAP STABILITAS
ENZIM ?-AMILASE DARI Bacillus subtilis ITBCCB148
%X ABSTRAK

Enzim ?-amilase merupakan enzim yang penting dalam bidang pangan,
bioteknologi dan industri serta berperan dalam hidrolisis amilum dengan memutus
ikatan ?-1,4 glikosida. Pada bidang industri, enzim ini harus mampu bekerja pada
pH ekstrim dengan stabilitas termal yang tinggi, namun pada umumnya enzim
tidak stabil pada kondisi tersebut.
Tujuan penelitian ini adalah untuk mempelajari pengaruh penambahan
sorbitol terhadap stabilitas enzim ?-amilase dari Bacillus subtilis ITBCCB148.
Untuk mencapai tujuan tersebut, telah dilakukan berbagai tahap yaitu : produksi,
isolasi, serta pemurnian secara fraksinasi ammonium sulfat dan dialisis. Aktivitas
enzim ?-amilase ditentukan dengan metode Fuwa dan Mandels sedangkan kadar
protein enzim ditentukan dengan metode Lowry.
Hasil penelitian menunjukan bahwa enzim hasil pemurnian memiliki
aktivitas spesifik sebesar 4185,70 U/mg, meningkat 11 kali dibandingkan ekstrak
kasar enzim dengan aktivitas spesifik sebesar 373,559 U/mg. Enzim hasil
pemurnian ini memiliki pH optimum 6,5; suhu 60?C; nilai KM = 9
?mol/mL.menit; Vmaks = 500 ?mol/mL.menit, nilai ki = 0,029 menit-1; t1/2 =
23,896 menit; ?Gi = 103,009 KJ mol-1. Uji stabilitas termal enzim setelah
penambahan sorbitol 0,5 M memiliki nilai KM = 3,4 ?mol/mL.menit, Vmaks = 200
?mol/mL.menit, nilai ki = 0,021 menit-1; t1/2 = 33 menit; ?Gi = 103,903 KJ mol-1,
sorbitol 1,0 M memiliki nilai KM = 4,95 ?mol/mL.menit, Vmaks = 333,333
?mol/mL.menit, nilai ki = 0,016 menit-1; t1/2 = 43,312 menit; ?Gi = 104,312 KJ
mol-1, dan sorbitol 1,5 M memiliki nilai KM = 7,5 ?mol/mL.menit, Vmaks = 500
?mol/mL.menit, nilai ki = 0,012 menit-1; t1/2 = 57,75 menit; ?Gi = 105,452 KJ
mol-1.
Penambahan sorbitol terhadap enzim ?-amilase dari Bacillus subtilis
ITBCCB148 menunjukan peningkatan stabilitas termal enzim berdasarkan
peningkatan waktu paruh dan ?Gi serta turunnya nilai ki.
Kata Kunci : ?-amilase, Bacillus subtilis ITBCCB148, sorbitol.

ABSTRACT

?-amylase is an enzyme that is important in the field of food,
biotechnology, and industry as well as play a role in the hydrolysis of starch, to
break the ?-1,4 glycoside. In a specific industry, this enzyme must be capable of
working at extreme pH with high thermal stability, but in general the enzyme is
not stable in these condition.
The purpose of this research was to study the effects of sorbitol on the
stability of the enzyme ?-amylase from Bacillus subtilis ITBCCB148. To achieve
these objectives, it has been carried out a number of stages, i.e: production,
isolation, and purification by ammonium sulfate fractination and dialysis. The
enzyme activity was determined by the method of Fuwa and Mandels while the
enzyme protein content determined by the method of Lowry.
The results showed that the purified enzyme has a specific activity of
4185.7 U/mg, an increased of 11 fold compared to crude extract of the enzyme
with a specific activity of 373.559 U/mg. Purified enzyme has a pH optimum 6.5;
temperature 60?C; KM= 9 ?mol/mL.sec; Vmax= 500 ?mol/mL.sec; ki = 0.029 sec-1;
t1/2 = 23.896 sec; ?Gi = 103.009 KJ.mol-1. Kinetic data of the enzyme after the
addition of 0.5 M sorbitol has the KM= 3.4 ?mol/mL.sec; Vmax = 200
?mol/mL.sec; ki = 0.021 sec-1; t1/2 = 33 sec; ?Gi = 103.903 KJ.mol-1, addition of
1.0 M sorbitol has the KM= 4.95 ?mol/mL.sec; Vmax = 333.333 ?mol/mL.sec; ki =
0.016 sec-1; t1/2 = 43.312 sec; ?Gi = 104.312 KJ.mol-1; and addition of sorbitol 1.5
M has the KM= 7.5 ?mol/mL.sec; Vmax = 500 ?mol/mL.sec; ki = 0.012 sec-1; t1/2 =
57.75 sec; and ?Gi = 105.452 KJ.mol-1.
The addition of sorbitol to the ?-amylase from Bacillus subtilis
ITBCCB148 showed increase the thermal stability of the enzyme which showed
on an increment in half-life ?Gi and capability to decrease the ki value.
Keyword : ?-amylase, Bacillus subtilis ITBCCB148, sorbitol.


%C UNIVERSITAS LAMPUNG
%D 2016
%I FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
%L eprints24719