How dynamically edit field in kendo grid

Question

I want to change editable property of the field, but this way it doesn't work. How can I fix this?

function changeDescription(rawGrid, isEditableDescription) {
        var grid = rawGrid.data("kendoGrid");
        if (!grid) return;

        if (isEditableDescription) {
            grid.dataSource.options.schema.model.fields["Description"].editable = true;
        }
        else {
            grid.dataSource.options.schema.model.fields["Description"].editable = false;
        }
    }