TY - JOUR
T1 - Studies on the amino groups of myosin ATPase IV. Effect of ATP and its analogs on the spectral properties of trinitrophenylated myosin and its active fragments
AU - Muhlrad, Andras
PY - 1977/7/22
Y1 - 1977/7/22
N2 - A considerable blue shift was observed in the absorption spectrum of the trinitrophenyl moiety attached to a functional ε-lysyl amino group of subfragment-1, heavy meromyosin and myosin on addition of ATP or ATP analogs. The resulting difference spectra showed a maximum at 320 and a minimum at 365 nm. The greatest spectral change was observed with a non-hydrolyzable ATP analog, adenosine 5′-(β,γ-imino)triphosphate and it decreased in the order adenosine 5′-(β,γ-imino)triphosphate, ATP and ADP. The ATP-induced difference spectrum changed to that of ADP upon the hydrolysis of ATP. The observed spectra were dependent on temperature and ionic strength. Difference spectra were produced also by ITP, IDP and pyrophosphate while AMP was practically ineffective. Mg2+ also caused small spectral changes which are not identical with those induced by ATP analogs. On the basis of measurements carried out on a model compound, it is assumed that as a consequence of the reaction of ATP with a myosin head, the environment of the functional lysyl residue becomes less polar, i.e. it becomes buried in the hydrophobic core of the molecule. Changes on addition of ATP or its analogs were observed also in the circular dichroic (CD) spectrum of trinitrophenylated subfragment-1, which also points to conformational changes in the vicinity of the functional lysyl residue.
AB - A considerable blue shift was observed in the absorption spectrum of the trinitrophenyl moiety attached to a functional ε-lysyl amino group of subfragment-1, heavy meromyosin and myosin on addition of ATP or ATP analogs. The resulting difference spectra showed a maximum at 320 and a minimum at 365 nm. The greatest spectral change was observed with a non-hydrolyzable ATP analog, adenosine 5′-(β,γ-imino)triphosphate and it decreased in the order adenosine 5′-(β,γ-imino)triphosphate, ATP and ADP. The ATP-induced difference spectrum changed to that of ADP upon the hydrolysis of ATP. The observed spectra were dependent on temperature and ionic strength. Difference spectra were produced also by ITP, IDP and pyrophosphate while AMP was practically ineffective. Mg2+ also caused small spectral changes which are not identical with those induced by ATP analogs. On the basis of measurements carried out on a model compound, it is assumed that as a consequence of the reaction of ATP with a myosin head, the environment of the functional lysyl residue becomes less polar, i.e. it becomes buried in the hydrophobic core of the molecule. Changes on addition of ATP or its analogs were observed also in the circular dichroic (CD) spectrum of trinitrophenylated subfragment-1, which also points to conformational changes in the vicinity of the functional lysyl residue.
UR - http://www.scopus.com/inward/record.url?scp=0017716651&partnerID=8YFLogxK
U2 - 10.1016/0005-2795(77)90268-9
DO - 10.1016/0005-2795(77)90268-9
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C2 - 141948
AN - SCOPUS:0017716651
SN - 0005-2795
VL - 493
SP - 154
EP - 166
JO - BBA - Protein Structure
JF - BBA - Protein Structure
IS - 1
ER -