In detergents which are enzyme based, enzymes can target certain stains caused by specific molecules, whilst leaving the fabric itself alone. This allows it to break down the stain without actually damaging the fabric itself (which is the case with many chemical detergents). This also allows you to wash clothes at a much lower temperature, as most enzymes peak activity is around 35 degrees Celsius. A disadvantage of using enzymes in detergent is that someone may not realise that they MUST wash clothes at a lower temperature. If the temperature is too high, the enzymes active site will denature and therefore not work at breaking down stains.