Atle shareholders will decide whether to accept the £580m takeover put forward by 3i and Ratos in February this year.
Mercury Private Equity Fund and US firm SAIC Venture Capital Corporation led the round.
The size of the fund will allow the private equity firm to "follow companies all the way through from initial investment," according to its managing director.
Senior debt and working capital was provided by Bank of Scotland, Intermediate Capital Group provided mezzanine finance and the remaining investment came from existing shareholders.
Christopher Wright, head of Dresdner Kleinwort Capital, says he is confident about Dresdner Bank's merger with Allianz as well as the future of his private equity business.
Advent Venture Partners led the placement which included previous investors Atlas Venture, Schroder Ventures, 3i and Abingworth.
The group has named Derek Gardner, previously of NatWest Equity Partners, as director of the enlarged office.
Global Equity Partners and Go Equity also participated in the round.
The fund, with an E1bn target, will make 10 to 15 investments of up to E300m, most of which as part of its buy-and-build strategy.
The level of investment into the UK has increased from the fourth quarter of last year but figures for the whole year are unlikely to reach the same level as 2000.