No real idea, but may be ask this person? https://www.researchgate.net/publication/7389303_The_PMDB_Protein_Model_Database?ev=srch_pub&_sg=HStAZjqQvQ8ClvZkMhakVGO2Q7Z3HqUHGpleYw42aNRDt1zUlnB0I1R1xU6NVHZE_wLLSbCw0KhQjYvPCTqhAIoBwoj8HSeXYecyAdGROdZVs5lbgoFp15Mg1LEdDN4oG