using map() to convert json data to an object

I have data service which returns fake data as json (private mockData function). Since json data structure matches MyPerson object I'm trying to cast that json data to MyPerson object simple using .map(res => res as MyPerson)); This doesn't work cause I'm getting error that data cannot be converted to MyPerson object.

My question is: how can I map this json data to MyPerson object using map function?

@Injectable()
export class DataService {
    person: MyPerson;

    constructor(private http: Http) {
        this.person = new MyPerson();
    }

    getData(): Observable<MyPerson> {
        return Observable.from([this.mockData()]
            .map(res => res as MyPerson)); /// ERROR?
    }

    private mockData() {
        return {
            "Id": 100,
            "firstName": "John",
            "lastName": "Conor",         
            "address": {
                "postalAddress": {
                    "Streetline": "Long street",
                    "Suburb": "some suburb",
                    "City": "Boston",
                    "Province": "MA"
                },
                "residentialAddress": {
                    "Streetline": "Short street",
                    "Suburb": "my suburb",
                    "City": "New Jersey",
                    "Province": "N/A"
                }
            },
            "Status": OK            
        }
    };
}

 export class MyPerson {
        Id: number;    
        firstName: string;
        lastName: string;    
        address: {
            residentalAddress: Address;
            postalAddress: Address;
        }    
    }

export class Address {    
    public StreetAddress: string;
    public Suburb: string;
    public City: string;
    public Province: string;

    constructor(street: string, suburb: string, city: string, province: string){
        this.StreetAddress = street;
        this.Suburb = suburb;
        this.City = city;
        this.Province = province;
    }
}