In 1957 together with Andrey Nikolayevich Belozersky he conducted comparative analysis of bacterial DNA and RNA, and predicted existence of messenger RNA. He gave the first qualitative description of the structure of high-polymer RNA (1959-61). In 1963 he discovered the structural transitions of ribosomes and formulated one of the principles of structure of ribosomes. He discovered an artificial ribosomal self-assembly (1963-66). Proposed a molecular mechanism of the ribosome role in protein synthesis (1968). He conducted an extra-cellular protein synthesis on modified ribosomes — non-enzymatic translation (together with L.P. Gavrilova) (1970-74).
Dr. Spirin was awarded Hans Adolf Krebs medal in 1969, elected Honorary Fellow of University of Granada in 1972.