Phosphofructokinase (PFK) is an important enzyme in virtually all living cells. It performs the committed step in the glycolytic pathway, namely, the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. Glycolysis is a pathway that uses glucose to maintain a steady amount of ATP, the major energy carrier in living cells. Phosphofructokinase is a multisubunit protein. In such proteins, the subunits may behave cooperatively; that is, the activity of one subunit influences the activity of all the other subunits. Proteins that exhibit this behavior are known as allosteric proteins.
What is a 'Variable Cost'. A variable cost is a corporate expense that varies with production output. Variable costs are those costs that vary depending on a company's production volume; they rise as production increases and fall as production decreases. Variable costs differ from fixed costs such as rent, advertising, insurance and office supplies, which tend to remain the same regardless of production output.
A variable cost is a cost that varies in relation to either production volume or services provided. If there is no production or no services are provided, then there should be no variable costs.To calculate total variable costs, the formula is:Total quantity of units produced x Variable cost per unit = Total variable cost. Direct materials are considered a variable cost. Direct labor may not be a variable cost if labor is not added to or subtracted from the production process as production volumes change. variable cost is a cost that varies in relation to either production volume or services provided. If there is no production or no services are provided, then there should be no variable costs. To calculate total variable costs, the formula is: