So it's going to be load restricted if it is the 77L, about 70% of MTOW, as page 10 of this document describes (approximately 3,300m required for MTOW at MSL on a standard day of 15 degrees C, QNH 1013 HPA, Density 1.225 kg per m3)
http://www.boeing.com/assets/pdf/com...s/7772sec3.pdf
Edited to add of course DUB-LAX would require nowhere near max fuel load for a full pax cabin, but they would be unable to go to MTOW by adding cargo