Anita Zabludowicz, the exhibitionist

Artists representing their countries at the Venice Biennale hope to win the Lion d'Or, but the most coveted prize for the rest of the art world is the multicoloured leather wristband that allows you unlimited access to art collector Anita Zabludowicz's 120ft yacht. Chartered for those crucial opening days of the Biennale and moored four boats down from Roman Abramovich's tank-like vessel

The Zabludowicz Collection of contemporary art is housed in the couple's private museum, a converted Methodist Chapel, at 176 Prince of Wales Road in Chalk Farm. Comprising over 2,000 works by 350 artists from 33 countries, the collection, according to Anita, provides material for conversation and experimentation. 'There's nothing more boring than plonking art down somewhere,' she says in her soft Geordie accent.Their four-year-old practice focuses on residencies for artists and curators, who are invited to use the space and collection as inspiration for new exhibitions. A team, led by director Elizabeth Neilson, works with galleries 'who nurture their artists rather than hype them', and unlike most other collectors, the Zabludowiczes don't off-load their acquisitions and don't follow the market; they operate entirely as philanthropists. 'The idea is that you want to collect an artist till the day you die. I'm looking for a journey with an artist, and that takes commitment. You want not just to acquire them but to get to know them, they become part of my "art family", I watch them grow.' But Anita's reach extends beyond her own collection. A trustee of the Tate and Camden Arts Centre, and a sponsor of Whitechapel Gallery, she has also been signed up by Boris Johnson as a fundraiser and creative force behind the Queen Elizabeth Olympic Park. 'Boris turned up at 176 three years ago on his bicycle,' she says, 'and told me about his plans for the Olympic Park after 2012. They were a bit generic and unimaginative so I told him they were rubbish. He loved that and said, "You do it, then." ' And Anita was made chairman of the development board for the Legacy List.

The London Legacy List is the charity set up by the Mayor of London's office to oversee the integration of artists into the fabric of the Olympic Park and to look after it once the Games have ended. 'We wanted to build a park hosting the Olympics,' she says, 'and not vice versa. We have a fantastic space, with accommodation for 10,000, 40 per cent of which is social housing. There's a Westfield shopping centre, community centres, schools - the OLPC has given us money to create artworks, education projects, a creative hub with artists' studios and a floating cinema, and we have a more than usual amount of fairy dust to sprinkle, so the playgrounds will be wonderful and we're hoping for a waterfall. I feel like I'm doing something,' she adds.

We have now left the yacht and skirted the fenced-off area around the Abramovich boat, which has a wooden checkpoint with policemen on walkie-talkies. There has been much discussion of the Russian billionaire's presence at this Biennale: how was he able to impose his boat on the city in this way? 'Money,' people mutter gloomily over their Bellinis. But although Luna has become the Biennale's most talked-about installation and the super-rich are here in droves, so are the young and the politically motivated, and as Anita and I enter the Giardini we spot many earnest young art lovers with their 'Free Ai Weiwei' bags. Anita takes a photograph of a plump Chinese man in drag before we begin our tour of the pavilions, led by Neilson.

'I think they should have a Geordie pavilion,' muses Anita as we begin on the group show curated by this year's Biennale director Bice Curiger. 'Bice is great,' she says. 'She came to see round the Olympic Park...' Then Anita is distracted by the sight of pigeons - the work of Spanish artist Maurizio Cattelan - congregating ominously on beams and skylights. Anita laughs: 'Look, that one's about to poo on the painting underneath!' She ponders a particularly minimal work and asks Neilson to explain, having confessed: 'I don't get it; I have to learn. It's a challenge, especially if I don't like something.' In a room full of Cindy Sherman self-portraits of the artist as other people, Anita says, 'We have some works of Cindy's, bought in the 1990s, but we didn't continue. If I buy a Sherman, I have to sacrifice 20 or 30 young artists. What really excites me is to buy artists young, straight out of college.' As if on cue, she exclaims, 'Haroon!' and kisses a young man warmly on each cheek.

Haroon Mirza is one of Anita's favourite discoveries: 'I first saw his work at an MA collaboration [with Laura Buckley] at 176. I immediately recognised something I loved. He looks at how objects relate to each other through sound and technology - a really original use of banal materials Will you customise a bicycle helmet, Haroon?' she asks, proffering a contract for him to sign. The London Legacy List charity is to launch on 26 September at the Four Seasons, where Sotheby's will hold an auction of bicycle helmets enhanced by artists. Keith Tyson, Tracey Emin and Marc Quinn are already committed, and during the day Anita signs up some more. 'I was inspired by the Boris bikes,' she says, before asking Haroon to talk us through his work. He points out how soundtrack affects the way you look at things, and shows us a film of what appears to be a festival but is actually footage of the recent riots outside Fortnum & Mason. 'I love it,' says Anita. The work later wins Mirza the Silver Lion for promising young artist.

We head off to a talk for Tate Patrons at the British Pavilion. As a trustee of the Tate Foundation since Tate Modern opened in 1997, Anita has an emotional investment in the institution. 'Poju did the most amazing thing for my 40th birthday - he made a substantial gift to Tate Modern. You only do things like that when you're dead. There's a gallery named after me.'

Anita was born in Newcastle to Mr and Mrs Harry Steinman 51 years ago. Her mother was an art lover who would drag her only child to exhibitions, and Harry was a well-known local wholesale businessman. 'I loved Newcastle life; there was no class system, no snobbery. The doors were always open on our street and we played outside. Later I worked in my dad's warehouse in Byker, but I was very artistic and wrote poetry so I went to art college to study fine art and art history.' She then attended the Inchbald School of Design in London, studying interior architecture, financially supported by her father. She was 25 years old and working as a project manager when she met Poju, who had gate-crashed her best friend's engagement party. They married soon after. Born in Helsinki, Poju was a property tycoon well on his way to becoming one of the richest men in London. He has led the global equity firm Tamares since 1990, is a generous Tory party donor, is said to own 40 per cent of central Las Vegas and was number 18 on the 2009 Sunday Times Rich List, with an estimated fortune of £1,500 million. 'When we started a family,' recalls Anita, 'I quit my job and started studying modern art and auctioneering at Christie's. Poju was also interested in art and, when we were ready, we started collecting.' They bought their first piece, by Ben Nicholson, in the early 1990s. They didn't know anyone in the art world, but had good social connections. Richard Branson's sister Vanessa introduced them to Nicholas Serota, who in turn introduced them to the curator Thomas Dane. 'Thomas masterminded our collection, he really showed us the way.'

After Poju met the cutting-edge New York artist Matthew Barney, the couple switched to collecting contemporary art 'just like that', according to Anita. But it has taken years for them to be considered seriously by the art world. Money and good intentions aren't enough; galleries like to 'place' their art in particular museums and collections because a work's provenance is intrinsic to its market value and that of the artist. 'I was on the waiting list at Victoria Miro for a Peter Doig painting from 1995 until 2009. When they finally offered me one, I turned it down!' In a way, this has been a good thing, steering the couple towards young emerging artists and away from the obvious. 'Not many private institutions can do what we do; we're like an art lab, we have great freedom.'

Back on the yacht, she introduces me to Pavel S Pys, the winner of her first annual curatorial open exhibition. Pavel is curating this month's show, We Will Live, We Will See. Anita describes him as 'a rising star', adding, 'He won't need my help after this.'

This is Anita's fourth Biennale, and she has noticed changes. 'It's become like Art Basel in Miami Beach - all about money and the parties; event-driven. The art gets lost, which is a real shame. What's the point of coming to these things just for the parties? I can't understand it.'