


	Stated Fixed Interest Rate		Effective Interest Rate		Principal Balance
	Stated Fixed Interest Rate		Effective Interest Rate		June 30, 2011			December 31, 2010			Maturity Date
Mortgage Notes Payable
Ardentech Court (1)	7.25	%	5.06	%	$	—		$	4,237		July 1, 2012
Center for Life Science \| Boston	7.75	%	7.75	%	343,896			345,577			June 30, 2014
500 Kendall Street (Kendall D)	6.38	%	5.45	%	63,261			64,230			December 1, 2018
6828 Nancy Ridge Drive	7.15	%	5.38	%	6,430			6,488			September 1, 2012
Road to the Cure (1)	6.70	%	5.78	%	—			14,696			January 31, 2014
10255 Science Center Drive (1)	7.65	%	5.04	%	—			10,800			July 1, 2011
Shady Grove Road	5.97	%	5.97	%	147,000			147,000			September 1, 2016
Sidney Street	7.23	%	5.11	%	26,907			27,395			June 1, 2012
Sorrento West LLC	7.42	%	2.72	%	13,112			13,247			November 10, 2011
9865 Towne Centre Drive (2)	7.95	%	7.95	%	17,528			17,636			June 30, 2013
900 Uniqema Boulevard	8.61	%	5.61	%	915			1,011			May 1, 2015
					619,049			652,317
Unamortized premiums					4,072			5,605
Mortgage notes payable, net					623,121			657,922
Notes due 2026	4.50	%	6.45	%	19,800			19,800			October 1, 2026
Unamortized discount (3)					(94		)	(278		)
Notes due 2026, net (4)					19,706			19,522
Notes due 2030	3.75	%	3.75	%	180,000			180,000			January 15, 2030
Exchangeable senior notes, net					199,706			199,522
Notes due 2016	3.85	%	3.99	%	400,000			—			April 15, 2016
Unamortized discount (5)					(2,424		)	—
Notes due 2016, net					397,576			—
Notes due 2020	6.13	%	6.27	%	250,000			250,000			April 15, 2020
Unamortized discount (6)					(2,330		)	(2,429		)
Notes due 2020, net					247,670			247,571
Unsecured senior notes, net					645,246			247,571
Unsecured line of credit (7)	1.29	%	1.29	%	121,200			392,450			July 13, 2015
Total consolidated debt					$	1,589,273		$	1,497,465

____________

(1)

During the six months ended June 30, 2011, the Operating Partnership voluntarily prepaid in full the outstanding mortgage notes totaling approximately $30.1 million pertaining to the Ardentech Court, Road to the Cure, and 10255 Science Center Drive properties, prior to their respective maturity dates.

(2)	In July 2011, the Operating Partnership voluntarily prepaid in full the outstanding mortgage note pertaining to the 9865 Towne Centre Drive property, in the amount of approximately $17.9 million including a prepayment premium of $351,000, prior to its maturity date.

(3)	The unamortized debt discount will be amortized through October 1, 2011, the first date at which the holders of the Notes due 2026 may require the Operating Partnership to repurchase the Notes due 2026.

(4)	As of June 30, 2011 and December 31, 2010, the carrying value of the equity component recognized was approximately $14.0 million.

(5)	The unamortized debt discount will be amortized through April 15, 2016, the maturity date of the Notes due 2016.

(6)	The unamortized debt discount will be amortized through April 15, 2020, the maturity date of the Notes due 2020.

(7)

At June 30, 2011, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $591.0 million (net of outstanding letters of credit issued by the Operating Partnership and drawable on the unsecured line of credit of approximately $7.8 million). On July 14, 2011, the Operating Partnership entered into a new $750.0 million unsecured line of credit, replacing its existing line of credit, as described below in this Note 5.