sed - Separate date and time with a comma -

i have access log lines

http://***.com ,**.**.**.**,2013-06-07 12:03:58 ,mozilla/5.0 (windows nt 6.1; wow64; rv:21.0) gecko/20100101 firefox/21.0.  

i need date , time separated comma using sed

seems want this,

$ sed 's/\([0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}\) \([0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}\)/\1,\2/g' file http://***.com ,**.**.**.**,2013-06-07,12:03:58 ,mozilla/5.0 (windows nt 6.1; wow64; rv:21.0) gecko/20100101 firefox/21.0.  

• \([0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}\) capture date string.
• match in-between space character.
• \([0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}\) capture time string.
• then replace matched strings \1 characters inside group index 1, , \2 characters inside group index 2.
• \(\) called capturing group in basic regular expressions. example \([0-9]\{4\}\) capture 4 digit number group.