A Wall Street investment bank, Deutsche Bank, hopes that a series of recent acquisitions will make it a major player in the alternative mortgage market. Last week, Deutsche Bank announced that it has agreed to pay an estimated $429 million to acquire wholesale lender MortgageIT. The New York-based lender operates out of 50 branches around the country and touts itself as one of the fastest growing lenders in the U.S., with originations that have…