{'fraction_non_alphanumeric': 0.01880456682337139, 'fraction_numerical': 0.002686366689053056, 'mean_word_length': 5.592920353982301, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Force generation in muscle: time‐resolved measurements of atpase activity using a phosphate‐sensitive fluorophore

The speed and efficiency of chemomechanical transduction appear to be well matched to contractile function in muscle and other cell types. When active, the contractile proteins myosin and actin convert chemical energy from the hydrolysis of ATP into mechanical work, a process that involves sequential dissociation of the products of ATP hydrolysis from the actomyosin complex. An improved understanding of chemomechanical transduction has emerged only slowly from experimental study, since it is difficult to perform biochemical measurements in an intact contractile system, and it is virtually impossible to reliably place mechanical loads on contractile protein biochemical assay systems in solution. These are important limitations, since it is probable that the transitional rate constants of one or more steps in the ATPase cycle vary with mechanical stress or strain. In recent years, the use of chemically caged compounds such as ATP, Ca¥ and inorganic phosphate (Pé) has circumvented these limitations to a significant degree: rapid photolysis of caged compounds can be used to probe force-generating transitions in both skeletal and cardiac muscle. For example, studies with caged Pé now suggest that force development in muscle involves one or more cross-bridge transitions (most probably an isomerization) kinetically coupled to Pé release (Dantzig et al. 1992).