Boston's biggest real estate players have secured nearly a half-billion dollars in financing for an East Cambridge lab play.

The Davis Cos. and Principal Global Investors have secured a $491M loan from Blackstone Mortgage Trust for their acquisition and conversion of a two-building office asset, Commercial Observer reports. The buildings, Charles Park One and Two across from the CambridgeSide Mall, cover 405K SF and sit near the airtight Kendall Square market.

Principal, which has owned the properties since 2004, retains a stake in the deal with Davis for the financing, which came at a 65% loan-to-cost ratio, Commercial Observer reported. The Davis Cos. didn't respond to a request for comment Thursday afternoon.

Charles Park Two, the 252K SF building built in 1989, is 100% leased while the smaller Charles Park One built in 1995 spans 130K SF, features smaller floor plates and is 81% leased, Principal reported as of February. The developers plan to convert the property to a lab facility for multiple tenants, according to CO.

The properties sit in the tight East Cambridge market, where Colliers reported just 4.4% vacancy among 20.2M SF of office and lab in a Q4 2020 report.

Blackstone's various arms are placing billions of dollars around in the booming Boston life sciences market, recently recapitalizing a $3.1B portfolio of 17 buildings, two-thirds of which are in Cambridge. The private equity giant recapitalized BioMed Realty Trust for $14.6B last year, and in December bought a $3.5B Brookfield portfolio concentrated in Cambridge.