ATP and Enzyme Properties
ATP is your body's energy currency! When ATP is hydrolyzed (broken down), it releases approximately 30.5 kJ/mol of energy that can power other reactions. For example, transporting 9 sodium ions requires about 91.5 kJ of energy, meaning 3 ATP molecules must be hydrolyzed to power this process.
Similarly, synthesizing sucrose from glucose and fructose requires 27.2 kJ of energy. One ATP hydrolysis provides 30.5 kJ, which is more than enough! This demonstrates how cells couple energy-releasing reactions (ATP breakdown) to energy-requiring reactions (sucrose synthesis).
Enzymes make these coupling reactions possible, but they're picky about their working conditions. Enzymes require specific conditions to function properly. When conditions aren't ideal, enzymes begin to denature, changing their structure and losing function. Once human enzymes denature, they cannot properly couple reactions anymore.
Important to know: The second level of protein folding (involving hydrogen bonds) is the weakest and most easily disrupted by environmental changes. This makes enzymes sensitive to factors like temperature and pH.
Different levels of protein folding contribute to enzyme stability. The third level involves hydrogen bonds and can change under stress, while the fourth level involves multiple polypeptides bonding together. Understanding these structures helps explain why enzymes work only under specific conditions.