TY  - JOUR
AU  - Fitter, J.
AU  - Herrmann, N. A.
AU  - Dencher, N. A.
AU  - Blume, A.
AU  - Hauß, N. A.
TI  - Activity and stability of a thermostable alpha-amylase compared to its mesophilic homologue : mechanisms of thermal adaptation
JO  - Biochemistry
VL  - 40
SN  - 0006-2960
CY  - Columbus, Ohio
PB  - American Chemical Society
M1  - PreJuSER-696
SP  - 10723 - 10731
PY  - 2001
N1  - Record converted from VDB: 12.11.2012
AB  - To elucidate how enzymes adapt to extreme environmental conditions, a comparative study with a thermostable alpha-amylase from Bacillus licheniformis (BLA) and its mesophilic homologue from Bacillus amyloliquefaciens (BAA) was performed. We measured conformational stability, catalytic activity, and conformational fluctuations on the picosecond time scale for both enzymes as a function of temperature. The objective of this study is to analyze how these properties are related to each other. BLA shows its maximal catalytic activity at about 90-95 degrees C and a strongly reduced activity (only 20% of the maximum) at room temperature. Although B. licheniformis itself is a mesophilic organism, BLA shows an activity profile typical for a thermophilic enzyme. In contrast to this, BAA exhibits its maximal activity at about 80 degrees C but with a level of about 60% activity at room temperature. In both cases the unfolding temperatures T(m) are only 6 degrees C (BAA, T(m) = 86 degrees C) and 10 degrees C (BLA, T(m) = 103 degrees C), respectively, higher than the temperatures for maximal activity. In contrast to many previous studies on other thermophilic-mesophilic pairs, in this study a higher structural flexibility of the thermostable BLA was measured as compared to the mesophilic BAA. The findings of this study neither indicate a proportionality between the observed dynamics and the catalytic activity nor support the idea of more "rigid" thermostable proteins, as often proposed in the concept of "corresponding states".
KW  - Bacillus: enzymology
KW  - Catalysis
KW  - Enzyme Stability
KW  - Hot Temperature
KW  - Models, Molecular
KW  - Protein Conformation
KW  - Spectrometry, Fluorescence
KW  - Structure-Activity Relationship
KW  - Temperature
KW  - alpha-Amylases: chemistry
KW  - alpha-Amylases: metabolism
KW  - alpha-Amylases (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:11524019
UR  - <Go to ISI:>//WOS:000170731900038
DO  - DOI:10.1021/bi010808b
UR  - https://juser.fz-juelich.de/record/696
ER  -