SQL & PL/SQL

Hi ,
I have a sql like

select TRIM(column_name)
    from user_tab_columns
    where table_name = 'MTL_SYSTEM_ITEMS_VL' AND COLUMN_NAME   IN ('DESCRIPTION     ');

no rows selected

But if i remove the spaces after 'DESCRIPTION'

select TRIM(column_name)
    from user_tab_columns
    where table_name = 'MTL_SYSTEM_ITEMS_VL' AND COLUMN_NAME   IN ('DESCRIPTION');

One Row Selected 

Like this i have many rows .
What clause other than trim i should apply to no cosider the spaces?

Thanks