"I've been reading a lot of posts about folks having trouble using grain. I'm no expert, but I did work in a brewery for 10 years after being a home brewer for 6 or 7, and here are a few things that may, (or may not), be of use.
When using grains, you only need to crack open the grain, not pulverize it. I shoot for no more than 10% powder. More than that and you run the risk of a stuck run off. Don't start your run off until the starch has converted, use the iodine test or just let the grains soak at 152-158 for about an hour. The starch should all be converted by then. When you start the run off. Go slow at first and put the wort back on top of the grain's until it comes out nice and clear. If it's pulverized you can do neither. During the run off add 160-170 water over the top and depending on how deep your grain bed is you may want to ""cut the bed"", just a spoon handle no more that 50% deep should suffice. Run off until the wort is about 5.5, (no higher than 5.7) ph. Higher and your running tannins into your brew."

The kernels of the malted grains have the enzymes to convert the starch to sugar. The enzymes are formed during the malting process.