PMID- 9879670
OWN - NLM
STAT- MEDLINE
DCOM- 19990323
LR  - 20190818
IS  - 0300-8177 (Print)
IS  - 0300-8177 (Linking)
VI  - 189
IP  - 1-2
DP  - 1998 Dec
TI  - Enzymatic properties of overexpressed human hexokinase fragments.
PG  - 185-93
AB  - Full-length hexokinase (HK; ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1), a 
      truncate form of the enzyme lacking the first 11 amino acids (HK-11aa) and the 50 
      kDa C-terminal half ('mini'-HK) containing the catalytic domain, were 
      overexpressed and purified to homogeneity to investigate the influence of the 
      N-terminal region of human hexokinase type I (HK) on its regulatory properties. 
      All forms of the enzyme are catalytically active with the HK-11aa being the most 
      active. All the forms of HK showed the same affinity for glucose and MgATP and 
      were also inhibited by glucose 6-phosphate (Glc 6-P) competitively vs. MgATP with 
      similar Kis (28.5-37 microM). Glucose 1,6-bisphosphate (Glc 1,6-P2) was also a 
      strong inhibitor of all HKs without significant differences among the different 
      truncate forms of the enzyme (Kis 49.5-59 microM). At low concentrations (0-3 
      mM), Pi was able to reverse the sugar phosphate inhibition of the full-length HK 
      and HK-11aa but not of the 'mini'-HK. In contrast, at high concentrations Pi was 
      an inhibitor of all the hexokinases investigated. These findings confirm that Pi 
      has a low affinity binding site on the C-terminal of HK while counteracts glucose 
      6-phosphate inhibition by binding to or requiring the N-terminal half of the 
      enzyme. The first 11 N-terminal amino acids influence the specific activity of HK 
      but are unable to affect the kinetic properties investigated.
FAU - Bianchi, M
AU  - Bianchi M
AD  - Institute of Biological Chemistry G Fornaini, University of Urbino, Italy.
FAU - Serafini, G
AU  - Serafini G
FAU - Bartolucci, E
AU  - Bartolucci E
FAU - Giammarini, C
AU  - Giammarini C
FAU - Magnani, M
AU  - Magnani M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Mol Cell Biochem
JT  - Molecular and cellular biochemistry
JID - 0364456
RN  - 0 (Phosphates)
RN  - 56-73-5 (Glucose-6-Phosphate)
RN  - EC 2.7.1.1 (Hexokinase)
SB  - IM
MH  - Dose-Response Relationship, Drug
MH  - Electrophoresis, Polyacrylamide Gel
MH  - Glucose-6-Phosphate/antagonists & inhibitors
MH  - Hexokinase/isolation & purification/*metabolism
MH  - Humans
MH  - Hydrogen-Ion Concentration
MH  - Kinetics
MH  - Models, Biological
MH  - Phosphates/pharmacology
MH  - Plasmids/genetics
MH  - Spectrophotometry
EDAT- 1999/01/08 00:00
MHDA- 1999/01/08 00:01
CRDT- 1999/01/08 00:00
PHST- 1999/01/08 00:00 [pubmed]
PHST- 1999/01/08 00:01 [medline]
PHST- 1999/01/08 00:00 [entrez]
AID - 10.1023/a:1006962217495 [doi]
PST - ppublish
SO  - Mol Cell Biochem. 1998 Dec;189(1-2):185-93. doi: 10.1023/a:1006962217495.